derivative 2

Question

Find the derivative of f(x) =  at x = 1.

Answer 1

f(x) =7/x

      =7x^-1

Using the formula:d/dx(x^n) =nx^(n-1)

f'(x) =7 d/dx(x^-1)

       =7(-1x^(-1-1))

       =-7 x^-2

       =-7/x^2

At x=1

f'(1) =-7/1^2

        =-7

f'(1) =-7