Build the idea
Differentiation measures instantaneous change. NDA questions reward recognising the outermost operation: products need the product rule, quotients the quotient rule, and nested functions the chain rule. Simplify algebraically before differentiating whenever possible.
Concept
Differentiation gives the instantaneous rate of change (slope) of a function. The standard rules — power, product, quotient and chain — let you differentiate almost any combination of functions.
Mastering the rules makes calculus questions quick and mechanical.
Key Points & Formulas
- d/dx(xⁿ) = n x^(n−1); d/dx(sinx)=cosx; d/dx(eˣ)=eˣ; d/dx(lnx)=1/x.
- Product rule: (uv)' = u'v + uv'.
- Quotient rule: (u/v)' = (u'v − uv')/v².
- Chain rule: dy/dx = (dy/du)(du/dx).
Worked Example
Q. Differentiate y = x³ ln x with respect to x.
Product rule with u = x³, v = ln x.
dy/dx = (3x²)(ln x) + (x³)(1/x).
= 3x² ln x + x².
