Question

Differentiate each of the following from first principles:

1/√(3 - x)

Answer 1

We need to find derivative of f(x) = 1/√(3 – x)

Derivative of a function f(x) from first principle is given by –

{where h is a very small positive number}

∴ derivative of f(x) = 1/√(3 – x) is given as –

Multiplying numerator and denominator by √(3 – x) + √(3 – x – h) to rationalise the expression so that we don’t get any indeterminate form after putting value of h