Question

another question!

Answer 1

f(x+h)=-4(x+h)-7
f(x+h)=-4x-4h-7
f(x+h)-f(x)=-4x-4h-7+4x+7
f(x+h)-f(x)=-4h
f(x+h)-f(x)/h=-4

if h->0 then
f(x+h)-f(x)/h=-4

which is exactly the derivater of f(x)

Answer 2

thanks

Answer 3

@trotay97