Graph Transformations: y = af(x + b) + c
Adjust the parameters in the graph above to explore the relationships between variables.
A function maps each element of a set (the domain) to exactly one element of another set (the Codomain). If f ( x ) = 3 x + 2 f(x) = 3x + 2 f ( x ) = 3 x + 2 Then f f f takes an input x x x and returns 3 x + 2 3x + 2 3 x + 2 . The notation f : A → B f \colon A \to B f : A → B means f f f maps from set A A A to set B B B .
Domain and Range:
The domain of f f f is the set of all valid inputs. The range is the set of all outputs.
The domain of f ( x ) = 1 x − 3 f(x) = \dfrac{1}{x - 3} f ( x ) = x − 3 1 is x ∈ R x \in \mathbb{R} x ∈ R , x ≠ 3 x \neq 3 x = 3 .
The range of f ( x ) = x 2 f(x) = x^2 f ( x ) = x 2 is f ( x ) ≥ 0 f(x) \geq 0 f ( x ) ≥ 0 (assuming the domain is all real numbers).
Composite Functions:
If f ( x ) = 2 x + 1 f(x) = 2x + 1 f ( x ) = 2 x + 1 and g ( x ) = x 2 g(x) = x^2 g ( x ) = x 2 Then:
f ( g ( x ) ) = f ( x 2 ) = 2 x 2 + 1 f(g(x)) = f(x^2) = 2x^2 + 1 f ( g ( x )) = f ( x 2 ) = 2 x 2 + 1
g ( f ( x ) ) = g ( 2 x + 1 ) = ( 2 x + 1 ) 2 = 4 x 2 + 4 x + 1 g(f(x)) = g(2x + 1) = (2x + 1)^2 = 4x^2 + 4x + 1 g ( f ( x )) = g ( 2 x + 1 ) = ( 2 x + 1 ) 2 = 4 x 2 + 4 x + 1
Note that f ( g ( x ) ) ≠ g ( f ( x ) ) f(g(x)) \neq g(f(x)) f ( g ( x )) = g ( f ( x )) . Composition is not commutative.
Domain of a composite function: dom ( f ∘ g ) \operatorname{dom}(f \circ g) dom ( f ∘ g ) is the set of all x x x in dom ( g ) \operatorname{dom}(g) dom ( g ) such that g ( x ) ∈ dom ( f ) g(x) \in \operatorname{dom}(f) g ( x ) ∈ dom ( f ) .
Inverse Functions:
The inverse function f − 1 f^{-1} f − 1 reverses the effect of f f f . To find f − 1 f^{-1} f − 1 :
Write y = f ( x ) y = f(x) y = f ( x ) Rearrange to make x x x the subject Replace x x x with f − 1 ( y ) f^{-1}(y) f − 1 ( y ) Example: Find f − 1 f^{-1} f − 1 where f ( x ) = 2 x + 3 x − 1 f(x) = \dfrac{2x + 3}{x - 1} f ( x ) = x − 1 2 x + 3 .
Let y = 2 x + 3 x − 1 y = \dfrac{2x + 3}{x - 1} y = x − 1 2 x + 3 .
y ( x − 1 ) = 2 x + 3 y(x - 1) = 2x + 3 y ( x − 1 ) = 2 x + 3
y x − y = 2 x + 3 yx - y = 2x + 3 y x − y = 2 x + 3
y x − 2 x = y + 3 yx - 2x = y + 3 y x − 2 x = y + 3
x ( y − 2 ) = y + 3 x(y - 2) = y + 3 x ( y − 2 ) = y + 3
x = y + 3 y − 2 x = \frac{y + 3}{y - 2} x = y − 2 y + 3
Therefore f − 1 ( x ) = x + 3 x − 2 f^{-1}(x) = \dfrac{x + 3}{x - 2} f − 1 ( x ) = x − 2 x + 3 .
Verification: f ( f − 1 ( x ) ) = 2 ⋅ x + 3 x − 2 + 3 x + 3 x − 2 − 1 = 2 x + 6 + 3 x − 6 x − 2 x + 3 − x + 2 x − 2 = 5 x 5 = x f(f^{-1}(x)) = \dfrac{2 \cdot \frac{x+3}{x-2} + 3}{\frac{x+3}{x-2} - 1} = \dfrac{\frac{2x+6+3x-6}{x-2}}{\frac{x+3-x+2}{x-2}} = \dfrac{5x}{5} = x f ( f − 1 ( x )) = x − 2 x + 3 − 1 2 ⋅ x − 2 x + 3 + 3 = x − 2 x + 3 − x + 2 x − 2 2 x + 6 + 3 x − 6 = 5 5 x = x . Confirmed.
The domain of f − 1 f^{-1} f − 1 equals the range of f f f And vice versa. A function has an inverse if and Only if it is a bijection (both one-to-one and onto). For functions R → R \mathbb{R} \to \mathbb{R} R → R This means the function must be strictly monotone.
A quadratic function has the general form f ( x ) = a x 2 + b x + c f(x) = ax^2 + bx + c f ( x ) = a x 2 + b x + c where a ≠ 0 a \neq 0 a = 0 .
Completed Square Form:
f ( x ) = a ( x − p ) 2 + q f(x) = a(x - p)^2 + q f ( x ) = a ( x − p ) 2 + q
Where the vertex is at ( p , q ) (p, q) ( p , q ) . The axis of symmetry is the vertical line x = p x = p x = p .
Derivation. Starting from a x 2 + b x + c ax^2 + bx + c a x 2 + b x + c :
A x 2 + b x + c = a ( x 2 + b a x ) + c = a ( x + b 2 a ) 2 − b 2 4 a + c Ax^2 + bx + c = a\!\left(x^2 + \frac{b}{a}x\right) + c = a\!\left(x + \frac{b}{2a}\right)^2 - \frac{b^2}{4a} + c A x 2 + b x + c = a ( x 2 + a b x ) + c = a ( x + 2 a b ) 2 − 4 a b 2 + c So p = − b 2 a p = -\frac{b}{2a} p = − 2 a b and q = c − b 2 4 a q = c - \frac{b^2}{4a} q = c − 4 a b 2 .
Example: Express f ( x ) = 2 x 2 − 12 x + 7 f(x) = 2x^2 - 12x + 7 f ( x ) = 2 x 2 − 12 x + 7 in completed square form.
f ( x ) = 2 ( x 2 − 6 x ) + 7 f(x) = 2(x^2 - 6x) + 7 f ( x ) = 2 ( x 2 − 6 x ) + 7
f ( x ) = 2 ( ( x − 3 ) 2 − 9 ) + 7 f(x) = 2\left((x - 3)^2 - 9\right) + 7 f ( x ) = 2 ( ( x − 3 ) 2 − 9 ) + 7
f ( x ) = 2 ( x − 3 ) 2 − 18 + 7 f(x) = 2(x - 3)^2 - 18 + 7 f ( x ) = 2 ( x − 3 ) 2 − 18 + 7
f ( x ) = 2 ( x − 3 ) 2 − 11 f(x) = 2(x - 3)^2 - 11 f ( x ) = 2 ( x − 3 ) 2 − 11
The vertex is at ( 3 , − 11 ) (3, -11) ( 3 , − 11 ) and since a = 2 > 0 a = 2 > 0 a = 2 > 0 The parabola opens upward with a minimum value of − 11 -11 − 11 .
The Discriminant:
For a x 2 + b x + c = 0 ax^2 + bx + c = 0 a x 2 + b x + c = 0 The discriminant is Δ = b 2 − 4 a c \Delta = b^2 - 4ac Δ = b 2 − 4 a c .
Condition Number of Roots Δ > 0 \Delta > 0 Δ > 0 Two distinct real roots Δ = 0 \Delta = 0 Δ = 0 One repeated real root Δ < 0 \Delta < 0 Δ < 0 No real roots
Proof. The quadratic formula gives x = − b ± Δ 2 a x = \frac{-b \pm \sqrt{\Delta}}{2a} x = 2 a − b ± Δ . If Δ > 0 \Delta > 0 Δ > 0 The Square root is real and positive, yielding two distinct values. If Δ = 0 \Delta = 0 Δ = 0 Both values are − b 2 a -\frac{b}{2a} − 2 a b . If Δ < 0 \Delta < 0 Δ < 0 The square root is not real.
Example: Determine the nature of the roots of 3 x 2 − 5 x + 2 = 0 3x^2 - 5x + 2 = 0 3 x 2 − 5 x + 2 = 0 .
Δ = ( − 5 ) 2 − 4 ( 3 ) ( 2 ) = 25 − 24 = 1 \Delta = (-5)^2 - 4(3)(2) = 25 - 24 = 1 Δ = ( − 5 ) 2 − 4 ( 3 ) ( 2 ) = 25 − 24 = 1
Since Δ > 0 \Delta > 0 Δ > 0 There are two distinct real roots.
Example: Find the value of k k k for which x 2 + k x + 9 = 0 x^2 + kx + 9 = 0 x 2 + k x + 9 = 0 has equal roots.
Δ = k 2 − 36 = 0 ⟹ k = ± 6 \Delta = k^2 - 36 = 0 \implies k = \pm 6 Δ = k 2 − 36 = 0 ⟹ k = ± 6
Laws of Logarithms:
log a ( x y ) = log a x + log a y \log_a(xy) = \log_a x + \log_a y log a ( x y ) = log a x + log a y
log a ( x y ) = log a x − log a y \log_a\left(\frac{x}{y}\right) = \log_a x - \log_a y log a ( y x ) = log a x − log a y
log a ( x n ) = n log a x \log_a(x^n) = n \log_a x log a ( x n ) = n log a x
log a a = 1 , log a 1 = 0 \log_a a = 1, \quad \log_a 1 = 0 log a a = 1 , log a 1 = 0
Change of Base:
log a b = log c b log c a \log_a b = \frac{\log_c b}{\log_c a} log a b = log c a log c b Proof of change of base. Let y = log a b y = \log_a b y = log a b So a y = b a^y = b a y = b . Taking log c \log_c log c of both sides: y log c a = log c b y \log_c a = \log_c b y log c a = log c b Hence y = log c b log c a y = \frac{\log_c b}{\log_c a} y = l o g c a l o g c b .
Example: Solve 3 2 x − 1 = 7 3^{2x - 1} = 7 3 2 x − 1 = 7 .
2 x − 1 = log 3 7 = ln 7 ln 3 2x - 1 = \log_3 7 = \frac{\ln 7}{\ln 3} 2 x − 1 = log 3 7 = l n 3 l n 7
2 x = 1 + ln 7 ln 3 2x = 1 + \frac{\ln 7}{\ln 3} 2 x = 1 + l n 3 l n 7
X = 1 2 ( 1 + ln 7 ln 3 ) ≈ 1.389 X = \frac{1}{2}\left(1 + \frac{\ln 7}{\ln 3}\right) \approx 1.389 X = 2 1 ( 1 + ln 3 ln 7 ) ≈ 1.389 Example: Solve log 2 ( x + 3 ) + log 2 ( x − 1 ) = 4 \log_2(x + 3) + \log_2(x - 1) = 4 log 2 ( x + 3 ) + log 2 ( x − 1 ) = 4 .
log 2 ( ( x + 3 ) ( x − 1 ) ) = 4 \log_2((x + 3)(x - 1)) = 4 log 2 (( x + 3 ) ( x − 1 )) = 4
( x + 3 ) ( x − 1 ) = 16 (x + 3)(x - 1) = 16 ( x + 3 ) ( x − 1 ) = 16
x 2 + 2 x − 3 = 16 x^2 + 2x - 3 = 16 x 2 + 2 x − 3 = 16
x 2 + 2 x − 19 = 0 x^2 + 2x - 19 = 0 x 2 + 2 x − 19 = 0
x = − 2 ± 4 + 76 2 = − 2 ± 80 2 = − 1 ± 2 5 x = \frac{-2 \pm \sqrt{4 + 76}}{2} = \frac{-2 \pm \sqrt{80}}{2} = -1 \pm 2\sqrt{5} x = 2 − 2 ± 4 + 76 = 2 − 2 ± 80 = − 1 ± 2 5
Since x + 3 > 0 x + 3 > 0 x + 3 > 0 and x − 1 > 0 x - 1 > 0 x − 1 > 0 We need x > 1 x > 1 x > 1 . So x = − 1 + 2 5 ≈ 3.472 x = -1 + 2\sqrt{5} \approx 3.472 x = − 1 + 2 5 ≈ 3.472 .
Exponential Growth and Decay:
N ( t ) = N 0 e k t N(t) = N_0 e^{kt} N ( t ) = N 0 e k t
Where N 0 N_0 N 0 is the initial quantity and k k k is the growth (k > 0 k > 0 k > 0 ) or decay (k < 0 k < 0 k < 0 ) constant.
Half-life: For decay with half-life t 1 / 2 t_{1/2} t 1/2 :
T 1 / 2 = ln 2 ∣ k ∣ T_{1/2} = \frac{\ln 2}{|k|} T 1/2 = ∣ k ∣ ln 2 Proof of the half-life formula. Set N ( t 1 / 2 ) = N 0 2 N(t_{1/2}) = \frac{N_0}{2} N ( t 1/2 ) = 2 N 0 :
N 0 2 = N 0 e k t 1 / 2 ⟹ 1 2 = e k t 1 / 2 ⟹ ln ( 1 2 ) = k t 1 / 2 \frac{N_0}{2} = N_0 e^{kt_{1/2}} \implies \frac{1}{2} = e^{kt_{1/2}} \implies \ln\!\left(\frac{1}{2}\right) = kt_{1/2} 2 N 0 = N 0 e k t 1/2 ⟹ 2 1 = e k t 1/2 ⟹ ln ( 2 1 ) = k t 1/2 − ln 2 = k t 1 / 2 ⟹ t 1 / 2 = − ln 2 k = ln 2 ∣ k ∣ -\ln 2 = kt_{1/2} \implies t_{1/2} = \frac{-\ln 2}{k} = \frac{\ln 2}{|k|} − ln 2 = k t 1/2 ⟹ t 1/2 = k − ln 2 = ∣ k ∣ ln 2 ■ \blacksquare ■
Example: A radioactive substance has a half-life of 8 days. If a sample initially contains 200 G, how much remains after 25 days?
K = ln 2 8 ≈ 0.0866 K = \frac{\ln 2}{8} \approx 0.0866 K = 8 ln 2 ≈ 0.0866 N(25) = 200e^{-0.0866 \times 25} = 200e^{-2.165} \approx 200 \times 0.1147 \approx 22.9 \mathrm{ g A polynomial of degree n n n has the form:
P ( x ) = a n x n + a n − 1 x n − 1 + ⋯ + a 1 x + a 0 P(x) = a_n x^n + a_{n-1} x^{n-1} + \cdots + a_1 x + a_0 P ( x ) = a n x n + a n − 1 x n − 1 + ⋯ + a 1 x + a 0 Factor Theorem:
( x − a ) (x - a) ( x − a ) is a factor of p ( x ) p(x) p ( x ) if and only if p ( a ) = 0 p(a) = 0 p ( a ) = 0 .
Remainder Theorem:
When p ( x ) p(x) p ( x ) is divided by ( x − a ) (x - a) ( x − a ) The remainder is p ( a ) p(a) p ( a ) .
Proof. By polynomial long division, p ( x ) = ( x − a ) q ( x ) + r p(x) = (x-a)q(x) + r p ( x ) = ( x − a ) q ( x ) + r for some quotient q ( x ) q(x) q ( x ) and constant Remainder r r r . Setting x = a x = a x = a : p ( a ) = 0 + r p(a) = 0 + r p ( a ) = 0 + r So r = p ( a ) r = p(a) r = p ( a ) .
Example: Factorise p ( x ) = x 3 − 3 x 2 − 4 x + 12 p(x) = x^3 - 3x^2 - 4x + 12 p ( x ) = x 3 − 3 x 2 − 4 x + 12 .
Try p ( 1 ) = 1 − 3 − 4 + 12 = 6 ≠ 0 p(1) = 1 - 3 - 4 + 12 = 6 \neq 0 p ( 1 ) = 1 − 3 − 4 + 12 = 6 = 0 .
Try p ( 2 ) = 8 − 12 − 8 + 12 = 0 p(2) = 8 - 12 - 8 + 12 = 0 p ( 2 ) = 8 − 12 − 8 + 12 = 0 . So ( x − 2 ) (x - 2) ( x − 2 ) is a factor.
P ( x ) = ( x − 2 ) ( x 2 − x − 6 ) = ( x − 2 ) ( x − 3 ) ( x + 2 ) P(x) = (x - 2)(x^2 - x - 6) = (x - 2)(x - 3)(x + 2) P ( x ) = ( x − 2 ) ( x 2 − x − 6 ) = ( x − 2 ) ( x − 3 ) ( x + 2 ) Example: Find the remainder when p ( x ) = 2 x 3 + x 2 − 5 x + 3 p(x) = 2x^3 + x^2 - 5x + 3 p ( x ) = 2 x 3 + x 2 − 5 x + 3 is divided by ( x + 1 ) (x + 1) ( x + 1 ) .
By the Remainder Theorem, the remainder is p ( − 1 ) p(-1) p ( − 1 ) :
P ( − 1 ) = 2 ( − 1 ) 3 + ( − 1 ) 2 − 5 ( − 1 ) + 3 = − 2 + 1 + 5 + 3 = 7 P(-1) = 2(-1)^3 + (-1)^2 - 5(-1) + 3 = -2 + 1 + 5 + 3 = 7 P ( − 1 ) = 2 ( − 1 ) 3 + ( − 1 ) 2 − 5 ( − 1 ) + 3 = − 2 + 1 + 5 + 3 = 7 Example: Given p ( x ) = x 3 + 2 x 2 − 5 x − 6 p(x) = x^3 + 2x^2 - 5x - 6 p ( x ) = x 3 + 2 x 2 − 5 x − 6 Show that ( x + 1 ) (x + 1) ( x + 1 ) is a factor and hence fully Factorise p ( x ) p(x) p ( x ) .
p ( − 1 ) = − 1 + 2 + 5 − 6 = 0 p(-1) = -1 + 2 + 5 - 6 = 0 p ( − 1 ) = − 1 + 2 + 5 − 6 = 0 . So ( x + 1 ) (x + 1) ( x + 1 ) is a factor.
By polynomial long division:
P ( x ) = ( x + 1 ) ( x 2 + x − 6 ) = ( x + 1 ) ( x + 3 ) ( x − 2 ) P(x) = (x + 1)(x^2 + x - 6) = (x + 1)(x + 3)(x - 2) P ( x ) = ( x + 1 ) ( x 2 + x − 6 ) = ( x + 1 ) ( x + 3 ) ( x − 2 ) Linear-Quadratic Systems:
Substitute the linear equation into the quadratic. The resulting equation is always a quadratic, Giving at most two solutions.
Example: Solve the system y = x 2 − 4 x + 3 y = x^2 - 4x + 3 y = x 2 − 4 x + 3 and 2 x + y = 6 2x + y = 6 2 x + y = 6 .
Substitute: 2 x + x 2 − 4 x + 3 = 6 2x + x^2 - 4x + 3 = 6 2 x + x 2 − 4 x + 3 = 6
x 2 − 2 x − 3 = 0 x^2 - 2x - 3 = 0 x 2 − 2 x − 3 = 0
( x − 3 ) ( x + 1 ) = 0 (x - 3)(x + 1) = 0 ( x − 3 ) ( x + 1 ) = 0
x = 3 \mathrm{ or x = -1
When x = 3 x = 3 x = 3 : y = 9 − 12 + 3 = 0 y = 9 - 12 + 3 = 0 y = 9 − 12 + 3 = 0 . When x = − 1 x = -1 x = − 1 : y = 1 + 4 + 3 = 8 y = 1 + 4 + 3 = 8 y = 1 + 4 + 3 = 8 .
Solutions: ( 3 , 0 ) (3, 0) ( 3 , 0 ) and ( − 1 , 8 ) (-1, 8) ( − 1 , 8 ) .
Given y = f ( x ) y = f(x) y = f ( x ) :
Transformation Effect y = f ( x ) + c y = f(x) + c y = f ( x ) + c Vertical translation by c c c units up y = f ( x − c ) y = f(x - c) y = f ( x − c ) Horizontal translation by c c c units right y = a f ( x ) y = af(x) y = a f ( x ) Vertical stretch by factor a a a y = f ( b x ) y = f(bx) y = f ( b x ) Horizontal stretch by factor 1 b \frac{1}{b} b 1 y = − f ( x ) y = -f(x) y = − f ( x ) Reflection in the x x x -axis y = f ( − x ) y = f(-x) y = f ( − x ) Reflection in the y y y -axis
The derivative of f ( x ) f(x) f ( x ) measures the instantaneous rate of change of f f f with respect to x x x . Geometrically, it gives the gradient of the tangent to the curve y = f ( x ) y = f(x) y = f ( x ) .
F ′ ( x ) = lim h → 0 f ( x + h ) − f ( x ) h F'(x) = \lim_{h \to 0} \frac{f(x + h) - f(x)}{h} F ′ ( x ) = h → 0 lim h f ( x + h ) − f ( x ) Standard Derivatives:
f ( x ) f(x) f ( x ) f ′ ( x ) f'(x) f ′ ( x ) x n x^n x n n x n − 1 nx^{n-1} n x n − 1 e k x e^{kx} e k x k e k x ke^{kx} k e k x ln x \ln x ln x 1 x \dfrac{1}{x} x 1 sin x \sin x sin x cos x \cos x cos x cos x \cos x cos x − sin x -\sin x − sin x
Differentiation Rules:
Sum/Difference: ( f ± g ) ′ = f ′ ± g ′ (f \pm g)' = f' \pm g' ( f ± g ) ′ = f ′ ± g ′
Product Rule: ( f g ) ′ = f ′ g + f g ′ (fg)' = f'g + fg' ( f g ) ′ = f ′ g + f g ′
Quotient Rule: ( f g ) ′ = f ′ g − f g ′ g 2 \left(\dfrac{f}{g}\right)' = \dfrac{f'g - fg'}{g^2} ( g f ) ′ = g 2 f ′ g − f g ′
Chain Rule: If y = f ( g ( x ) ) y = f(g(x)) y = f ( g ( x )) Then d y d x = f ′ ( g ( x ) ) ⋅ g ′ ( x ) \dfrac{dy}{dx} = f'(g(x)) \cdot g'(x) d x d y = f ′ ( g ( x )) ⋅ g ′ ( x )
Proof of the product rule. Define u ( x ) = f ( x ) g ( x ) u(x) = f(x)g(x) u ( x ) = f ( x ) g ( x ) . Then:
U ′ ( x ) = lim h → 0 f ( x + h ) g ( x + h ) − f ( x ) g ( x ) h U'(x) = \lim_{h \to 0} \frac{f(x+h)g(x+h) - f(x)g(x)}{h} U ′ ( x ) = h → 0 lim h f ( x + h ) g ( x + h ) − f ( x ) g ( x ) Add and subtract f ( x ) g ( x + h ) f(x)g(x+h) f ( x ) g ( x + h ) in the numerator:
= lim h → 0 f ( x + h ) g ( x + h ) − f ( x ) g ( x + h ) + f ( x ) g ( x + h ) − f ( x ) g ( x ) h = \lim_{h \to 0} \frac{f(x+h)g(x+h) - f(x)g(x+h) + f(x)g(x+h) - f(x)g(x)}{h} = h → 0 lim h f ( x + h ) g ( x + h ) − f ( x ) g ( x + h ) + f ( x ) g ( x + h ) − f ( x ) g ( x ) = lim h → 0 [ g ( x + h ) ⋅ f ( x + h ) − f ( x ) h + f ( x ) ⋅ g ( x + h ) − g ( x ) h ] = \lim_{h \to 0} \left[g(x+h) \cdot \frac{f(x+h) - f(x)}{h} + f(x) \cdot \frac{g(x+h) - g(x)}{h}\right] = h → 0 lim [ g ( x + h ) ⋅ h f ( x + h ) − f ( x ) + f ( x ) ⋅ h g ( x + h ) − g ( x ) ] = g ( x ) f ′ ( x ) + f ( x ) g ′ ( x ) = g(x)f'(x) + f(x)g'(x) = g ( x ) f ′ ( x ) + f ( x ) g ′ ( x ) Example: Differentiate f ( x ) = ( 3 x 2 + 1 ) sin ( 2 x ) f(x) = (3x^2 + 1)\sin(2x) f ( x ) = ( 3 x 2 + 1 ) sin ( 2 x ) using the product rule.
Let u = 3 x 2 + 1 u = 3x^2 + 1 u = 3 x 2 + 1 , v = sin ( 2 x ) v = \sin(2x) v = sin ( 2 x ) .
u ′ = 6 x u' = 6x u ′ = 6 x , v ′ = 2 cos ( 2 x ) v' = 2\cos(2x) v ′ = 2 cos ( 2 x ) .
F ′ ( x ) = 6 x sin ( 2 x ) + ( 3 x 2 + 1 ) ⋅ 2 cos ( 2 x ) F'(x) = 6x \sin(2x) + (3x^2 + 1) \cdot 2\cos(2x) F ′ ( x ) = 6 x sin ( 2 x ) + ( 3 x 2 + 1 ) ⋅ 2 cos ( 2 x ) F ′ ( x ) = 6 x sin ( 2 x ) + 2 ( 3 x 2 + 1 ) cos ( 2 x ) F'(x) = 6x \sin(2x) + 2(3x^2 + 1)\cos(2x) F ′ ( x ) = 6 x sin ( 2 x ) + 2 ( 3 x 2 + 1 ) cos ( 2 x ) Example: Differentiate f ( x ) = e 2 x x + 1 f(x) = \dfrac{e^{2x}}{x + 1} f ( x ) = x + 1 e 2 x .
Let u = e 2 x u = e^{2x} u = e 2 x , v = x + 1 v = x + 1 v = x + 1 .
u ′ = 2 e 2 x u' = 2e^{2x} u ′ = 2 e 2 x , v ′ = 1 v' = 1 v ′ = 1 .
F ′ ( x ) = 2 e 2 x ( x + 1 ) − e 2 x ( x + 1 ) 2 = e 2 x ( 2 x + 2 − 1 ) ( x + 1 ) 2 = e 2 x ( 2 x + 1 ) ( x + 1 ) 2 F'(x) = \frac{2e^{2x}(x + 1) - e^{2x}}{(x + 1)^2} = \frac{e^{2x}(2x + 2 - 1)}{(x + 1)^2} = \frac{e^{2x}(2x + 1)}{(x + 1)^2} F ′ ( x ) = ( x + 1 ) 2 2 e 2 x ( x + 1 ) − e 2 x = ( x + 1 ) 2 e 2 x ( 2 x + 2 − 1 ) = ( x + 1 ) 2 e 2 x ( 2 x + 1 ) Example: Differentiate f ( x ) = x 2 + 1 e 3 x f(x) = \dfrac{x^2 + 1}{e^{3x}} f ( x ) = e 3 x x 2 + 1 .
Let u = x 2 + 1 u = x^2 + 1 u = x 2 + 1 , v = e 3 x v = e^{3x} v = e 3 x .
u ′ = 2 x u' = 2x u ′ = 2 x , v ′ = 3 e 3 x v' = 3e^{3x} v ′ = 3 e 3 x .
F ′ ( x ) = 2 x ⋅ e 3 x − ( x 2 + 1 ) ⋅ 3 e 3 x e 6 x = e 3 x ( 2 x − 3 x 2 − 3 ) e 6 x = 2 x − 3 x 2 − 3 e 3 x F'(x) = \frac{2x \cdot e^{3x} - (x^2 + 1) \cdot 3e^{3x}}{e^{6x}} = \frac{e^{3x}(2x - 3x^2 - 3)}{e^{6x}} = \frac{2x - 3x^2 - 3}{e^{3x}} F ′ ( x ) = e 6 x 2 x ⋅ e 3 x − ( x 2 + 1 ) ⋅ 3 e 3 x = e 6 x e 3 x ( 2 x − 3 x 2 − 3 ) = e 3 x 2 x − 3 x 2 − 3 Setting f ′ ( x ) = 0 f'(x) = 0 f ′ ( x ) = 0 : 2 x − 3 x 2 − 3 = 0 2x - 3x^2 - 3 = 0 2 x − 3 x 2 − 3 = 0 I.e., 3 x 2 − 2 x + 3 = 0 3x^2 - 2x + 3 = 0 3 x 2 − 2 x + 3 = 0 . Since Δ = 4 − 36 = − 32 < 0 \Delta = 4 - 36 = -32 \lt 0 Δ = 4 − 36 = − 32 < 0 There are no real stationary points.
Stationary Points:
At a stationary point, f ′ ( x ) = 0 f'(x) = 0 f ′ ( x ) = 0 .
f ′ ( x ) f'(x) f ′ ( x ) changes from positive to negative: local maximum f ′ ( x ) f'(x) f ′ ( x ) changes from negative to positive: local minimum f ′ ( x ) f'(x) f ′ ( x ) does not change sign: point of inflection Second Derivative Test:
If f ′ ( a ) = 0 f'(a) = 0 f ′ ( a ) = 0 :
f ′ ′ ( a ) > 0 f''(a) > 0 f ′′ ( a ) > 0 : local minimum at x = a x = a x = a f ′ ′ ( a ) < 0 f''(a) < 0 f ′′ ( a ) < 0 : local maximum at x = a x = a x = a f ′ ′ ( a ) = 0 f''(a) = 0 f ′′ ( a ) = 0 : test is inconclusive — use the first derivative test insteadExample: Find the stationary points of f ( x ) = x 3 − 6 x 2 + 9 x + 1 f(x) = x^3 - 6x^2 + 9x + 1 f ( x ) = x 3 − 6 x 2 + 9 x + 1 and determine their nature.
F ′ ( x ) = 3 x 2 − 12 x + 9 = 3 ( x 2 − 4 x + 3 ) = 3 ( x − 1 ) ( x − 3 ) F'(x) = 3x^2 - 12x + 9 = 3(x^2 - 4x + 3) = 3(x - 1)(x - 3) F ′ ( x ) = 3 x 2 − 12 x + 9 = 3 ( x 2 − 4 x + 3 ) = 3 ( x − 1 ) ( x − 3 ) Stationary points at x = 1 x = 1 x = 1 and x = 3 x = 3 x = 3 .
F ′ ′ ( x ) = 6 x − 12 F''(x) = 6x - 12 F ′′ ( x ) = 6 x − 12 At x = 1 x = 1 x = 1 : f ′ ′ ( 1 ) = − 6 < 0 f''(1) = -6 < 0 f ′′ ( 1 ) = − 6 < 0 So local maximum. f ( 1 ) = 1 − 6 + 9 + 1 = 5 f(1) = 1 - 6 + 9 + 1 = 5 f ( 1 ) = 1 − 6 + 9 + 1 = 5 .
At x = 3 x = 3 x = 3 : f ′ ′ ( 3 ) = 6 > 0 f''(3) = 6 > 0 f ′′ ( 3 ) = 6 > 0 So local minimum. f ( 3 ) = 27 − 54 + 27 + 1 = 1 f(3) = 27 - 54 + 27 + 1 = 1 f ( 3 ) = 27 − 54 + 27 + 1 = 1 .
Local maximum at ( 1 , 5 ) (1, 5) ( 1 , 5 ) Local minimum at ( 3 , 1 ) (3, 1) ( 3 , 1 ) .
The tangent to y = f ( x ) y = f(x) y = f ( x ) at ( a , f ( a ) ) (a, f(a)) ( a , f ( a )) has equation:
Y − f ( a ) = f ′ ( a ) ( x − a ) Y - f(a) = f'(a)(x - a) Y − f ( a ) = f ′ ( a ) ( x − a ) The normal is perpendicular to the tangent and has gradient − 1 f ′ ( a ) -\dfrac{1}{f'(a)} − f ′ ( a ) 1 (provided f ′ ( a ) ≠ 0 f'(a) \ne 0 f ′ ( a ) = 0 ).
Example: Find the equation of the tangent to y = x 3 − 3 x + 1 y = x^3 - 3x + 1 y = x 3 − 3 x + 1 at x = 2 x = 2 x = 2 .
f ( 2 ) = 8 − 6 + 1 = 3 f(2) = 8 - 6 + 1 = 3 f ( 2 ) = 8 − 6 + 1 = 3 .
f ′ ( x ) = 3 x 2 − 3 f'(x) = 3x^2 - 3 f ′ ( x ) = 3 x 2 − 3 So f ′ ( 2 ) = 12 − 3 = 9 f'(2) = 12 - 3 = 9 f ′ ( 2 ) = 12 − 3 = 9 .
Y − 3 = 9 ( x − 2 ) ⟹ y = 9 x − 15 Y - 3 = 9(x - 2) \implies y = 9x - 15 Y − 3 = 9 ( x − 2 ) ⟹ y = 9 x − 15 Optimisation problems require you to express the quantity to be optimised as a function of a single Variable, then find the stationary points.
Example: A rectangular box with a square base has a volume of 128 \mathrm{ cm^3 . The material For the base costs 5 pence per \mathrm{cm^2 and the material for the sides costs 3 pence per \mathrm{cm^2 . Find the dimensions that minimise the cost.
Let the base have side length x x x cm and height h h h cm.
Volume: x 2 h = 128 x^2 h = 128 x 2 h = 128 So h = 128 x 2 h = \dfrac{128}{x^2} h = x 2 128 .
Cost: C = 5 x 2 + 4 × 3 x h = 5 x 2 + 12 x ⋅ 128 x 2 = 5 x 2 + 1536 x C = 5x^2 + 4 \times 3xh = 5x^2 + 12x \cdot \dfrac{128}{x^2} = 5x^2 + \dfrac{1536}{x} C = 5 x 2 + 4 × 3 x h = 5 x 2 + 12 x ⋅ x 2 128 = 5 x 2 + x 1536 .
d C d x = 10 x − 1536 x 2 \frac{dC}{dx} = 10x - \frac{1536}{x^2} d x d C = 10 x − x 2 1536 Setting d C d x = 0 \dfrac{dC}{dx} = 0 d x d C = 0 :
10 x = 1536 x 2 10x = \frac{1536}{x^2} 10 x = x 2 1536 10 x 3 = 1536 10x^3 = 1536 10 x 3 = 1536 X 3 = 153.6 X^3 = 153.6 X 3 = 153.6 X = \sqrt[3]{153.6} \approx 5.35 \mathrm{ cm H = \frac{128}{5.35^2} \approx 4.47 \mathrm{ cm Verification: d 2 C d x 2 = 10 + 3072 x 3 > 0 \frac{d^2C}{dx^2} = 10 + \frac{3072}{x^3} > 0 d x 2 d 2 C = 10 + x 3 3072 > 0 for all x > 0 x > 0 x > 0 Confirming a Minimum.
Example: A closed cylindrical can must hold 500 \mathrm{ cm^3 of liquid. Find the dimensions That minimise the surface area.
Let the radius be r r r and the height be h h h .
Volume: π r 2 h = 500 \pi r^2 h = 500 π r 2 h = 500 So h = 500 π r 2 h = \dfrac{500}{\pi r^2} h = π r 2 500 .
Surface area: S = 2 π r 2 + 2 π r h = 2 π r 2 + 1000 r S = 2\pi r^2 + 2\pi rh = 2\pi r^2 + \frac{1000}{r} S = 2 π r 2 + 2 π r h = 2 π r 2 + r 1000 .
d S d r = 4 π r − 1000 r 2 = 0 \frac{dS}{dr} = 4\pi r - \frac{1000}{r^2} = 0 d r d S = 4 π r − r 2 1000 = 0 4\pi r^3 = 1000 \implies r^3 = \frac{250}{\pi} \implies r = \sqrt[3]{\frac{250}{\pi}} \approx 4.30 \mathrm{ cm H = \frac{500}{\pi \times 4.30^2} \approx 8.60 \mathrm{ cm Note that h = 2 r h = 2r h = 2 r So the optimal can has height equal to diameter. d 2 S d r 2 = 4 π + 2000 r 3 > 0 \frac{d^2S}{dr^2} = 4\pi + \frac{2000}{r^3} > 0 d r 2 d 2 S = 4 π + r 3 2000 > 0 Confirming a minimum.
Integration is the reverse of differentiation.
∫ x n d x = x n + 1 n + 1 + C ( n ≠ − 1 ) \int x^n \, dx = \frac{x^{n+1}}{n+1} + C \quad (n \neq -1) ∫ x n d x = n + 1 x n + 1 + C ( n = − 1 ) ∫ e k x d x = e k x k + C \int e^{kx} \, dx = \frac{e^{kx}}{k} + C ∫ e k x d x = k e k x + C Definite Integration:
∫ a b f ( x ) d x = [ F ( x ) ] a b = F ( b ) − F ( a ) \int_a^b f(x) \, dx = \left[F(x)\right]_a^b = F(b) - F(a) ∫ a b f ( x ) d x = [ F ( x ) ] a b = F ( b ) − F ( a ) The Fundamental Theorem of Calculus. If F ′ ( x ) = f ( x ) F'(x) = f(x) F ′ ( x ) = f ( x ) on [ a , b ] [a, b] [ a , b ] Then ∫ a b f ( x ) d x = F ( b ) − F ( a ) \int_a^b f(x)\,dx = F(b) - F(a) ∫ a b f ( x ) d x = F ( b ) − F ( a ) . This theorem connects the two branches of calculus: Differentiation and integration are inverse operations.
Area Under a Curve:
The area between y = f ( x ) y = f(x) y = f ( x ) The x x x -axis, x = a x = a x = a And x = b x = b x = b is:
A = ∫ a b ∣ f ( x ) ∣ d x A = \int_a^b |f(x)| \, dx A = ∫ a b ∣ f ( x ) ∣ d x :::caution If the curve crosses the x x x -axis between a a a and b b b You must split the integral at Each crossing point and take the absolute value. The integral itself gives the signed area, which Can cancel out. :::
Example: Find the area enclosed by y = x 2 − 4 x + 3 y = x^2 - 4x + 3 y = x 2 − 4 x + 3 and the x x x -axis.
Find where the curve crosses the x x x -axis: x 2 − 4 x + 3 = ( x − 1 ) ( x − 3 ) = 0 x^2 - 4x + 3 = (x-1)(x-3) = 0 x 2 − 4 x + 3 = ( x − 1 ) ( x − 3 ) = 0 So x = 1 x = 1 x = 1 and x = 3 x = 3 x = 3 .
Since the parabola opens upward with roots at 1 and 3, the curve is below the x x x -axis between these Points.
A = ∫ 1 3 ∣ x 2 − 4 x + 3 ∣ d x = ∫ 1 3 ( 4 x − x 2 − 3 ) d x A = \int_1^3 |x^2 - 4x + 3| \, dx = \int_1^3 (4x - x^2 - 3) \, dx A = ∫ 1 3 ∣ x 2 − 4 x + 3∣ d x = ∫ 1 3 ( 4 x − x 2 − 3 ) d x = [ 2 x 2 − x 3 3 − 3 x ] 1 3 = \left[2x^2 - \frac{x^3}{3} - 3x\right]_1^3 = [ 2 x 2 − 3 x 3 − 3 x ] 1 3 = ( 18 − 9 − 9 ) − ( 2 − 1 3 − 3 ) = \left(18 - 9 - 9\right) - \left(2 - \frac{1}{3} - 3\right) = ( 18 − 9 − 9 ) − ( 2 − 3 1 − 3 ) = 0 − ( − 4 3 ) = 4 3 = 0 - \left(-\frac{4}{3}\right) = \frac{4}{3} = 0 − ( − 3 4 ) = 3 4 If f ( x ) ≥ g ( x ) f(x) \ge g(x) f ( x ) ≥ g ( x ) on [ a , b ] [a, b] [ a , b ] The area between the curves is:
A = ∫ a b [ f ( x ) − g ( x ) ] d x A = \int_a^b [f(x) - g(x)] \, dx A = ∫ a b [ f ( x ) − g ( x )] d x Example: Find the area between y = x 2 y = x^2 y = x 2 and y = 2 x y = 2x y = 2 x .
Find intersections: x 2 = 2 x x^2 = 2x x 2 = 2 x So x 2 − 2 x = 0 x^2 - 2x = 0 x 2 − 2 x = 0 Giving x = 0 x = 0 x = 0 and x = 2 x = 2 x = 2 .
Between x = 0 x = 0 x = 0 and x = 2 x = 2 x = 2 , 2 x > x 2 2x > x^2 2 x > x 2 .
A = ∫ 0 2 ( 2 x − x 2 ) d x = [ x 2 − x 3 3 ] 0 2 = 4 − 8 3 = 4 3 A = \int_0^2 (2x - x^2) \, dx = \left[x^2 - \frac{x^3}{3}\right]_0^2 = 4 - \frac{8}{3} = \frac{4}{3} A = ∫ 0 2 ( 2 x − x 2 ) d x = [ x 2 − 3 x 3 ] 0 2 = 4 − 3 8 = 3 4 Example: Find the area enclosed by the curves y = x 3 y = x^3 y = x 3 and y = x y = x y = x .
Find intersections: x 3 = x x^3 = x x 3 = x So x 3 − x = x ( x − 1 ) ( x + 1 ) = 0 x^3 - x = x(x-1)(x+1) = 0 x 3 − x = x ( x − 1 ) ( x + 1 ) = 0 Giving x = − 1 , 0 , 1 x = -1, 0, 1 x = − 1 , 0 , 1 .
Between x = − 1 x = -1 x = − 1 and x = 0 x = 0 x = 0 : x ≥ x 3 x \ge x^3 x ≥ x 3 (since x ∈ [ − 1 , 0 ] x \in [-1, 0] x ∈ [ − 1 , 0 ] means x ≥ x 3 x \ge x^3 x ≥ x 3 ). Between x = 0 x = 0 x = 0 And x = 1 x = 1 x = 1 : x 3 ≥ x x^3 \ge x x 3 ≥ x .
By symmetry of the two regions:
A = 2 ∫ 0 1 ( x 3 − x ) d x = 2 [ x 4 4 − x 2 2 ] 0 1 = 2 ( 1 4 − 1 2 ) = 2 ( − 1 4 ) = 1 2 A = 2\int_0^1 (x^3 - x)\, dx = 2\left[\frac{x^4}{4} - \frac{x^2}{2}\right]_0^1 = 2\!\left(\frac{1}{4} - \frac{1}{2}\right) = 2\!\left(-\frac{1}{4}\right) = \frac{1}{2} A = 2 ∫ 0 1 ( x 3 − x ) d x = 2 [ 4 x 4 − 2 x 2 ] 0 1 = 2 ( 4 1 − 2 1 ) = 2 ( − 4 1 ) = 2 1 \int f(g(x))g'(x) \, dx = \int f(u) \, du \quad \mathrm{where u = g(x) Example: Evaluate ∫ 2 x x 2 + 1 d x \int 2x\sqrt{x^2 + 1} \, dx ∫ 2 x x 2 + 1 d x .
Let u = x 2 + 1 u = x^2 + 1 u = x 2 + 1 So d u = 2 x d x du = 2x\,dx d u = 2 x d x .
∫ u d u = 2 3 u 3 / 2 + C = 2 3 ( x 2 + 1 ) 3 / 2 + C \int \sqrt{u}\, du = \frac{2}{3}u^{3/2} + C = \frac{2}{3}(x^2 + 1)^{3/2} + C ∫ u d u = 3 2 u 3/2 + C = 3 2 ( x 2 + 1 ) 3/2 + C Example: Evaluate ∫ 0 2 x x 2 + 1 d x \int_0^2 \frac{x}{x^2 + 1}\,dx ∫ 0 2 x 2 + 1 x d x .
Let u = x^2 + 1$$du = 2x\,dx . When x = 0$$u = 1 . When x = 2$$u = 5 .
∫ 0 2 x x 2 + 1 d x = 1 2 ∫ 1 5 1 u d u = 1 2 [ ln u ] 1 5 = 1 2 ln 5 \int_0^2 \frac{x}{x^2 + 1}\,dx = \frac{1}{2}\int_1^5 \frac{1}{u}\,du = \frac{1}{2}\left[\ln u\right]_1^5 = \frac{1}{2}\ln 5 ∫ 0 2 x 2 + 1 x d x = 2 1 ∫ 1 5 u 1 d u = 2 1 [ ln u ] 1 5 = 2 1 ln 5 ∫ u d v = u v − ∫ v d u \int u\, dv = uv - \int v\, du ∫ u d v = uv − ∫ v d u Use LIATE (Logarithmic, Inverse trig, Algebraic, Trigonometric, Exponential) to choose u u u .
Example: Evaluate ∫ x e x d x \int x e^x \, dx ∫ x e x d x .
Let u = x$$dv = e^x\,dx . Then du = dx$$v = e^x .
∫ x e x d x = x e x − ∫ e x d x = x e x − e x + C = e x ( x − 1 ) + C \int x e^x \, dx = xe^x - \int e^x \, dx = xe^x - e^x + C = e^x(x - 1) + C ∫ x e x d x = x e x − ∫ e x d x = x e x − e x + C = e x ( x − 1 ) + C A first-order differential equation relates a function to its first derivative.
Separable equations. If d y d x = f ( x ) g ( y ) \dfrac{dy}{dx} = f(x)g(y) d x d y = f ( x ) g ( y ) Separate the variables:
1 g ( y ) d y = f ( x ) d x \frac{1}{g(y)}\,dy = f(x)\,dx g ( y ) 1 d y = f ( x ) d x Integrate both sides.
Example: Solve d y d x = x y \dfrac{dy}{dx} = \dfrac{x}{y} d x d y = y x given y = 2 y = 2 y = 2 when x = 1 x = 1 x = 1 .
Separate: y d y = x d x y\,dy = x\,dx y d y = x d x .
Integrate: y 2 2 = x 2 2 + C \dfrac{y^2}{2} = \dfrac{x^2}{2} + C 2 y 2 = 2 x 2 + C .
Using y = 2 , x = 1 y = 2, x = 1 y = 2 , x = 1 : 2 = 1 2 + C 2 = \frac{1}{2} + C 2 = 2 1 + C So C = 3 2 C = \frac{3}{2} C = 2 3 .
y 2 = x 2 + 3 y^2 = x^2 + 3 y 2 = x 2 + 3 Giving y = x 2 + 3 y = \sqrt{x^2 + 3} y = x 2 + 3 (taking the positive root since y = 2 > 0 y = 2 > 0 y = 2 > 0 ).
See the examples integrated throughout the sections above.
Forgetting the chain rule: When differentiating sin ( 3 x ) \sin(3x) sin ( 3 x ) The answer is 3 cos ( 3 x ) 3\cos(3x) 3 cos ( 3 x ) Not cos ( 3 x ) \cos(3x) cos ( 3 x ) . Every composite function requires the chain rule.
Missing the + C +C + C : Always include the constant of integration for indefinite integrals. Omitting it is equivalent to asserting that you know the particular solution without initial conditions.
Sign errors in the product rule: It is f ′ g + f g ′ f'g + fg' f ′ g + f g ′ Not f ′ g − f g ′ f'g - fg' f ′ g − f g ′ . The minus sign belongs in the quotient rule.
Incorrect domain for logarithms: ln ( x ) \ln(x) ln ( x ) is only defined for x > 0 x > 0 x > 0 . Always check your solutions satisfy the domain restrictions. When solving log 2 ( x + 3 ) \log_2(x+3) log 2 ( x + 3 ) You need x > − 3 x > -3 x > − 3 .
Confusing f − 1 ( x ) f^{-1}(x) f − 1 ( x ) with 1 f ( x ) \dfrac{1}{f(x)} f ( x ) 1 : The notation f − 1 f^{-1} f − 1 denotes the inverse function, not the reciprocal. This is a notation collision that causes persistent confusion.
Forgetting absolute values in integrals of 1 / x 1/x 1/ x : ∫ d x x = ln ∣ x ∣ + C \int \frac{dx}{x} = \ln|x| + C ∫ x d x = ln ∣ x ∣ + C Not ln x + C \ln x + C ln x + C .
Not checking that optimisation solutions are minima: Always verify with the second derivative test or a sign chart.
Forgetting to change the limits when using substitution for definite integrals.
Sign error in the quotient rule: It is f ′ g − f g ′ g 2 \dfrac{f'g - fg'}{g^2} g 2 f ′ g − f g ′ Not f g ′ − f ′ g g 2 \dfrac{fg' - f'g}{g^2} g 2 f g ′ − f ′ g . “Low d-High minus High d-Low.”
Given f ( x ) = 2 x 2 − 8 x + 5 f(x) = 2x^2 - 8x + 5 f ( x ) = 2 x 2 − 8 x + 5 Express f ( x ) f(x) f ( x ) in completed square form and state the coordinates of the vertex.
Solve 4 x + 1 = 3 2 x − 1 4^{x+1} = 3^{2x-1} 4 x + 1 = 3 2 x − 1 Giving your answer in terms of natural logarithms.
Given p ( x ) = x 3 + 2 x 2 − 5 x − 6 p(x) = x^3 + 2x^2 - 5x - 6 p ( x ) = x 3 + 2 x 2 − 5 x − 6 Show that ( x + 1 ) (x + 1) ( x + 1 ) is a factor and hence fully factorise p ( x ) p(x) p ( x ) .
Differentiate f ( x ) = x 2 + 1 e 3 x f(x) = \dfrac{x^2 + 1}{e^{3x}} f ( x ) = e 3 x x 2 + 1 and find the coordinates of any stationary points.
Find the area enclosed by the curves y = x 3 y = x^3 y = x 3 and y = x y = x y = x .
A closed cylindrical can must hold 500 \mathrm{ cm^3 of liquid. Find the dimensions that minimise the surface area.
Solve log 3 ( x ) + log 3 ( x − 2 ) = 1 \log_3(x) + \log_3(x - 2) = 1 log 3 ( x ) + log 3 ( x − 2 ) = 1 .
Find the equation of the tangent to y = x 3 − 3 x + 1 y = x^3 - 3x + 1 y = x 3 − 3 x + 1 at the point where x = 2 x = 2 x = 2 .
Given f ( x ) = 1 3 x 3 − x 2 − 3 x + 2 f(x) = \frac{1}{3}x^3 - x^2 - 3x + 2 f ( x ) = 3 1 x 3 − x 2 − 3 x + 2 Find the intervals on which f f f is increasing and decreasing.
Evaluate ∫ 0 2 x x 2 + 1 d x \int_0^2 \frac{x}{x^2 + 1}\,dx ∫ 0 2 x 2 + 1 x d x using substitution.
The curve y = x 2 + p x + q y = x^2 + px + q y = x 2 + p x + q passes through ( 1 , 5 ) (1, 5) ( 1 , 5 ) and has a turning point at x = 2 x = 2 x = 2 . Find p p p and q q q .
Find the area between the curves y = x 2 + 1 y = x^2 + 1 y = x 2 + 1 and y = 3 x + 1 y = 3x + 1 y = 3 x + 1 .
Solve the differential equation d y d x = 2 x y \dfrac{dy}{dx} = 2xy d x d y = 2 x y given y = 5 y = 5 y = 5 when x = 0 x = 0 x = 0 .
Find the equation of the normal to y = x 2 − 4 x + 3 y = x^2 - 4x + 3 y = x 2 − 4 x + 3 at the point where x = 4 x = 4 x = 4 .
A population of bacteria grows according to P ( t ) = P 0 e 0.02 t P(t) = P_0 e^{0.02t} P ( t ) = P 0 e 0.02 t . If the initial population is 1000, how long does it take for the population to reach 5000?
Find the range of values of k k k for which x 2 + 2 k x + k 2 + 3 = 0 x^2 + 2kx + k^2 + 3 = 0 x 2 + 2 k x + k 2 + 3 = 0 has no real roots.
This topic covers the mathematical techniques and concepts related to algebra and calculus, including key theorems, methods, and problem-solving approaches.
Key concepts include:
quadratic equations and the discriminant simultaneous equations polynomial division and the factor theorem partial fractions binomial expansion Regular practice with a variety of question types is essential to build fluency and confidence in applying these mathematical techniques.