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MHF4U Formula Sheet · Grade 12 Advanced FunctionsOntario curriculum

Polynomial Functions

Polynomial function
f(x)=anxn+an−1xn−1+⋯+a1x+a0f(x) = a_nx^n + a_{n-1}x^{n-1} + \dots + a_1x + a_0

Degree nn, leading coefficient ana_n.

Transformed power function
y=a[k(x−d)]n+cy = a\big[k(x - d)\big]^n + c
Even function
f(−x)=f(x)f(-x) = f(x)

Symmetric about the yy-axis.

Odd function
f(−x)=−f(x)f(-x) = -f(x)

Symmetric about the origin.

Average rate of change
ΔyΔx=f(b)−f(a)b−a\frac{\Delta y}{\Delta x} = \frac{f(b) - f(a)}{b - a}
Instantaneous rate of change (estimate)
f(a+h)−f(a)h\frac{f(a + h) - f(a)}{h}

With hh very small.

Finite differences
Δny=a⋅n!\Delta^n y = a \cdot n!

For degree nn and equal xx steps of 1, the nnth differences are constant.

Polynomial Equations

Division statement
P(x)=D(x) Q(x)+R(x)P(x) = D(x)\,Q(x) + R(x)
Remainder theorem
P(x)÷(x−a) leaves remainder P(a)P(x) \div (x - a) \text{ leaves remainder } P(a)

Dividing by (ax−b)(ax - b) leaves P(ba)P\left(\frac{b}{a}\right).

Factor theorem
(x−a) is a factor of P(x)  ⟺  P(a)=0(x - a) \text{ is a factor of } P(x) \iff P(a) = 0
Rational zero test
x=bax = \frac{b}{a}

bb divides the constant term, aa divides the leading coefficient.

Sum of cubes
a3+b3=(a+b)(a2−ab+b2)a^3 + b^3 = (a + b)\left(a^2 - ab + b^2\right)
Difference of cubes
a3−b3=(a−b)(a2+ab+b2)a^3 - b^3 = (a - b)\left(a^2 + ab + b^2\right)

Rational Functions

Reciprocal function
y=1f(x)y = \frac{1}{f(x)}

Vertical asymptotes where f(x)=0f(x) = 0; invariant points where f(x)=±1f(x) = \pm 1.

Linear over linear
y=ax+bcx+dy = \frac{ax + b}{cx + d}

Vertical asymptote x=−dcx = -\frac{d}{c}, horizontal asymptote y=acy = \frac{a}{c}.

Horizontal asymptote
deg⁡N<deg⁡D: y=0deg⁡N=deg⁡D: y=ab\deg N < \deg D:\ y = 0 \qquad \deg N = \deg D:\ y = \frac{a}{b}

aa and bb are the leading coefficients of NN and DD. When deg⁡N=deg⁡D+1\deg N = \deg D + 1 there is an oblique asymptote instead: divide.

Hole
f(x)=(x−a) g(x)(x−a) h(x)f(x) = \frac{(x - a)\,g(x)}{(x - a)\,h(x)}

A factor that cancels gives a hole at x=ax = a, not an asymptote.

Trigonometric Ratios

Radians and degrees
π rad=180∘\pi \text{ rad} = 180^\circ
Arc length
a=rθa = r\theta

θ\theta in radians.

Special angles
sin⁡π6=12sin⁡π4=22sin⁡π3=32\sin\tfrac{\pi}{6} = \tfrac{1}{2} \qquad \sin\tfrac{\pi}{4} = \tfrac{\sqrt{2}}{2} \qquad \sin\tfrac{\pi}{3} = \tfrac{\sqrt{3}}{2}
Reciprocal ratios
csc⁡x=1sin⁡xsec⁡x=1cos⁡xcot⁡x=1tan⁡x\csc x = \frac{1}{\sin x} \qquad \sec x = \frac{1}{\cos x} \qquad \cot x = \frac{1}{\tan x}
Quotient identity
tan⁡x=sin⁡xcos⁡x\tan x = \frac{\sin x}{\cos x}
Pythagorean identity
sin⁡2x+cos⁡2x=1\sin^2 x + \cos^2 x = 1
Pythagorean identities, tan and cot
1+tan⁡2x=sec⁡2x1+cot⁡2x=csc⁡2x1 + \tan^2 x = \sec^2 x \qquad 1 + \cot^2 x = \csc^2 x
Co-function identities
sin⁡x=cos⁡(π2−x)cos⁡x=sin⁡(π2−x)\sin x = \cos\left(\frac{\pi}{2} - x\right) \qquad \cos x = \sin\left(\frac{\pi}{2} - x\right)
Shift by a quarter turn
sin⁡(x+π2)=cos⁡xcos⁡(x+π2)=−sin⁡x\sin\left(x + \frac{\pi}{2}\right) = \cos x \qquad \cos\left(x + \frac{\pi}{2}\right) = -\sin x
Compound angle, sine
sin⁡(x±y)=sin⁡xcos⁡y±cos⁡xsin⁡y\sin(x \pm y) = \sin x\cos y \pm \cos x\sin y
Compound angle, cosine
cos⁡(x±y)=cos⁡xcos⁡y∓sin⁡xsin⁡y\cos(x \pm y) = \cos x\cos y \mp \sin x\sin y
Double angle
sin⁡2x=2sin⁡xcos⁡xtan⁡2x=2tan⁡x1−tan⁡2x\sin 2x = 2\sin x\cos x \qquad \tan 2x = \frac{2\tan x}{1 - \tan^2 x}
Double angle, cosine
cos⁡2x=cos⁡2x−sin⁡2x=2cos⁡2x−1=1−2sin⁡2x\cos 2x = \cos^2 x - \sin^2 x = 2\cos^2 x - 1 = 1 - 2\sin^2 x

Trigonometric Functions

Sinusoidal function
y=asin⁡[k(x−d)]+cy=acos⁡[k(x−d)]+cy = a\sin\big[k(x - d)\big] + c \qquad y = a\cos\big[k(x - d)\big] + c
Period
period=2π∣k∣\text{period} = \frac{2\pi}{|k|}

For y=tan⁡kxy = \tan kx the period is π∣k∣\frac{\pi}{|k|}.

Amplitude and axis
∣a∣=max⁡−min⁡2c=max⁡+min⁡2|a| = \frac{\max - \min}{2} \qquad c = \frac{\max + \min}{2}
Asymptotes of tangent
y=tan⁡x:x=π2+nπ, n∈Zy = \tan x: \quad x = \frac{\pi}{2} + n\pi,\ n \in \mathbb{Z}

Exponential & Logarithmic Functions

Definition of a logarithm
y=bx  ⟺  x=log⁡byy = b^x \iff x = \log_b y

For b>0b > 0, b≠1b \neq 1, y>0y > 0.

Product law
log⁡b(MN)=log⁡bM+log⁡bN\log_b(MN) = \log_b M + \log_b N
Quotient law
log⁡b(MN)=log⁡bM−log⁡bN\log_b\left(\frac{M}{N}\right) = \log_b M - \log_b N
Power law
log⁡bMn=nlog⁡bM\log_b M^n = n\log_b M
Special values
log⁡b1=0log⁡bb=1blog⁡bx=x\log_b 1 = 0 \qquad \log_b b = 1 \qquad b^{\log_b x} = x
Change of base
log⁡bx=log⁡xlog⁡b\log_b x = \frac{\log x}{\log b}
Half-life
A(t)=A0(12)thA(t) = A_0\left(\frac{1}{2}\right)^{\frac{t}{h}}
Compound growth
A=P(1+i)nA = P(1 + i)^n
pH
pH=−log⁡[H+]\text{pH} = -\log\big[\text{H}^+\big]
Earthquake magnitude
M=log⁡(II0)M2−M1=log⁡(I2I1)M = \log\left(\frac{I}{I_0}\right) \qquad M_2 - M_1 = \log\left(\frac{I_2}{I_1}\right)
Sound level (decibels)
β=10log⁡(II0)β2−β1=10log⁡(I2I1)\beta = 10\log\left(\frac{I}{I_0}\right) \qquad \beta_2 - \beta_1 = 10\log\left(\frac{I_2}{I_1}\right)

Combining Functions

Sum and difference
(f±g)(x)=f(x)±g(x)(f \pm g)(x) = f(x) \pm g(x)

Domain: where both ff and gg are defined.

Product
(f⋅g)(x)=f(x) g(x)(f \cdot g)(x) = f(x)\,g(x)
Quotient
(fg)(x)=f(x)g(x)\left(\frac{f}{g}\right)(x) = \frac{f(x)}{g(x)}

Also exclude every xx where g(x)=0g(x) = 0.

Composition
(f∘g)(x)=f(g(x))(f \circ g)(x) = f\big(g(x)\big)

xx in the domain of gg and g(x)g(x) in the domain of ff.

Inverse check
(f∘f−1)(x)=x(f \circ f^{-1})(x) = x
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