How do you use the limit definition to find the derivative of y=-3x-3?

1 Answer
Oct 15, 2016

dy/dx=-3

Explanation:

By definition:
dy/dx=lim_(h->0)(f(x+h)-f(x))/h

so, with y=-3x-3 we have:

dy/dx=lim_(h->0)((((-3)(x+h)-3)-(-3x-3))/h)
:. dy/dx=lim_(h->0)((-3x -3h-3+3x+3)/h)
:. dy/dx=lim_(h->0)(-3h)/h
:. dy/dx=-3