EAPCET Mathematics · Intermediate first year · Paper IB

Differentiation

Differentiation builds the rules for finding derivatives: standard derivatives, product, quotient and chain rules, and implicit, parametric and logarithmic differentiation.

Subject
Mathematics
Taught in
Intermediate first year · Paper IB
Mathematics in the paper
80 of 160 questions

Key formulas and results

  • ddx(xn)=nxn−1\dfrac{d}{dx}(x^{n}) = nx^{n-1}
  • (uv)′=u′v+uv′(uv)' = u'v + uv' and (uv)′=u′v−uv′v2\left(\dfrac{u}{v}\right)' = \dfrac{u'v - uv'}{v^{2}}
  • Chain rule: dydx=dydu⋅dudx\dfrac{dy}{dx} = \dfrac{dy}{du} \cdot \dfrac{du}{dx}
  • ddx(sin⁡−1x)=11−x2\dfrac{d}{dx}(\sin^{-1}x) = \dfrac{1}{\sqrt{1 - x^{2}}}; ddx(tan⁡−1x)=11+x2\dfrac{d}{dx}(\tan^{-1}x) = \dfrac{1}{1 + x^{2}}
  • Parametric: dydx=dy/dtdx/dt\dfrac{dy}{dx} = \dfrac{dy/dt}{dx/dt}
  • ddx(xx)=xx(1+log⁡x)\dfrac{d}{dx}(x^{x}) = x^{x}(1 + \log x)

What this chapter covers

  • Derivatives from first principles
  • Product, quotient and chain rules
  • Derivatives of inverse trigonometric functions
  • Implicit and parametric differentiation
  • Logarithmic differentiation
  • Second-order derivatives

How it is usually asked

  • Differentiate a composite, implicit or parametric function
  • Find a second derivative
  • Differentiate a function raised to a variable power

Understanding Differentiation

The derivative f′(x) measures the instantaneous rate of change of f, defined from first principles as the limit of [f(x + h) − f(x)]/h as h → 0. In practice you rarely use the definition. Instead you memorise the derivatives of standard functions and combine them with rules: the sum rule, the product rule (uv)′ = u′v + uv′, the quotient rule and, most important, the chain rule for functions inside functions.

Some functions need special techniques. When y is given implicitly, as in x² + y² = 25, differentiate both sides with respect to x and treat y as a function of x. When x and y are both given in terms of a parameter t, dy/dx = (dy/dt)/(dx/dt). When the variable appears in both the base and the exponent, as in xˣ, take logarithms first and then differentiate.

Inverse trigonometric expressions often simplify with a substitution such as x = tan θ or x = sin θ before differentiating, which turns a long calculation into one line. EAPCET questions ask for first or second derivatives of composite, implicit, parametric and exponential-power functions, and they reward recognising these shortcuts rather than grinding through rules.

Worked example

EAPCET-style question

If y=tan⁡−12x1−x2y = \tan^{-1}\dfrac{2x}{1 - x^{2}} for ∣x∣<1|x| < 1, then dydx\dfrac{dy}{dx} equals

  1. (1)21+x2\dfrac{2}{1 + x^{2}}
  2. (2)11+x2\dfrac{1}{1 + x^{2}}
  3. (3)−21+x2-\dfrac{2}{1 + x^{2}}
  4. (4)2x1+x2\dfrac{2x}{1 + x^{2}}

Solution

  1. Put x=tan⁡θx = \tan\theta, so θ=tan⁡−1x\theta = \tan^{-1}x and θ\theta lies in (−π4,π4)\left(-\tfrac{\pi}{4}, \tfrac{\pi}{4}\right) because ∣x∣<1|x| < 1.
  2. Then 2x1−x2=2tan⁡θ1−tan⁡2θ=tan⁡2θ\dfrac{2x}{1 - x^{2}} = \dfrac{2\tan\theta}{1 - \tan^{2}\theta} = \tan 2\theta, with 2θ2\theta in (−π2,π2)\left(-\tfrac{\pi}{2}, \tfrac{\pi}{2}\right).
  3. So y=tan⁡−1(tan⁡2θ)=2θ=2tan⁡−1xy = \tan^{-1}(\tan 2\theta) = 2\theta = 2\tan^{-1}x.
  4. Differentiate: dydx=21+x2\dfrac{dy}{dx} = \dfrac{2}{1 + x^{2}}.

Answer: 21+x2\dfrac{2}{1 + x^{2}}

Common mistakes to avoid

  • Writing the quotient rule numerator as uv′ − u′v; the correct order is (u′v − uv′)/v².
  • Forgetting the derivative of the inside function in the chain rule, for example writing d/dx (sin 3x) = cos 3x instead of 3 cos 3x.
  • Differentiating aˣ like a power, as x aˣ⁻¹; the correct derivative is aˣ log a.
  • Finding d²y/dx² for parametric curves as (d²y/dt²)/(d²x/dt²); differentiate dy/dx with respect to t and then divide by dx/dt.

How to prepare it

For inverse-trigonometric expressions, a substitution like x = tan θ often simplifies the function before you differentiate.

Once the formulas feel familiar, test them the way the exam does: practise Differentiation questions chapter-wise, then attempt a full previous year paper to see whether it holds up under a 3-hour timer.

Related Mathematics chapters

See every chapter in the EAPCET Mathematics syllabus.

Practise Differentiation chapter-wise

Chapter-wise quizzes show exactly which topics in this chapter you still get wrong — before a full paper does.

Frequently asked questions

Is Differentiation part of the EAPCET Mathematics syllabus?
Yes. Differentiation is taught in Intermediate first year · Paper IB Mathematics, and the EAPCET Engineering syllabus is based on the Intermediate first- and second-year syllabus. Check the official notification each year for any changes.
How should I prepare Differentiation for EAPCET?
For inverse-trigonometric expressions, a substitution like x = tan θ often simplifies the function before you differentiate.
How many Mathematics questions are there in EAPCET?
80 of the 160 questions in the Engineering paper are Mathematics, spread across 37 chapters.
What mistakes do students make in Differentiation?
Writing the quotient rule numerator as uv′ − u′v; the correct order is (u′v − uv′)/v². Forgetting the derivative of the inside function in the chain rule, for example writing d/dx (sin 3x) = cos 3x instead of 3 cos 3x. Differentiating aˣ like a power, as x aˣ⁻¹; the correct derivative is aˣ log a. Finding d²y/dx² for parametric curves as (d²y/dt²)/(d²x/dt²); differentiate dy/dx with respect to t and then divide by dx/dt.