12Class 11 Maths

Limits and Derivatives formulas

Standard limits and derivative formulas. You'll use these all the way through Class 12 calculus.

Standard limits

Polynomial form
lim⁡x→axn−anx−a=nan−1\displaystyle \lim_{x \to a}\frac{x^n - a^n}{x - a} = na^{n - 1}
Sine
lim⁡x→0sin⁡xx=1\displaystyle \lim_{x \to 0}\frac{\sin x}{x} = 1

x in radians.

Cosine
lim⁡x→01−cos⁡xx=0\displaystyle \lim_{x \to 0}\frac{1 - \cos x}{x} = 0
Tangent
lim⁡x→0tan⁡xx=1\displaystyle \lim_{x \to 0}\frac{\tan x}{x} = 1

Derivatives

First principles
f′(x)=lim⁡h→0f(x+h)−f(x)h\displaystyle f'(x) = \lim_{h \to 0}\frac{f(x + h) - f(x)}{h}
Power
ddxxn=nxn−1\displaystyle \frac{d}{dx}x^n = nx^{n - 1}
Trigonometric
ddxsin⁡x=cos⁡x,ddxcos⁡x=−sin⁡x,ddxtan⁡x=sec⁡2x\displaystyle \frac{d}{dx}\sin x = \cos x, \quad \frac{d}{dx}\cos x = -\sin x, \quad \frac{d}{dx}\tan x = \sec^2x
Product rule
(uv)′=u′v+uv′\displaystyle (uv)' = u'v + uv'
Quotient rule
(uv)′=u′v−uv′v2\displaystyle \left(\frac{u}{v}\right)' = \frac{u'v - uv'}{v^2}

Where students slip up

  • Substituting straight away into a limit that gives 0/0. Simplify or factor first.
  • Using sin x / x → 1 with x in degrees. It only holds in radians.
  • Getting the order wrong in the quotient rule, since the minus makes it matter.

Try it on your weakest chapter.

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