Differential approximation (dy = f'(x)dx; Δy ≈ dy for small Δx)

jee-mainjee-advanced

dy = f'(x)dx; Δy ≈ dy for small Δx

What each symbol means

SymbolWhat it stands for
dxDifferential of x (think Δx small)
dyCorresponding change along tangent

When to use this

f differentiable; Δx small.