I know the derivative of x is 1, but I'm having a hard time proving it with the limit definition of the derivative.

Question

I have...

Lim delta x ->0 (x+ delta x)-(x)/delta x

= 0

But I know the answer is 1. I don't understand what I am doing wrong

Answer 1

(f(x+h) - f(x))/h
= ((x+h)-x)/h
= h/h
= 1

no need even to take the limit, since 1 is constant.