f(x) =3-5x?

Question

tangent line...
f(x+h) -f(x)/h
as the lim of h goes "0"

Answer 1

[(3-5(x+h))-(3-5x)]/h
= (3-5x -5h -3+5x)/h
= -5h/ h = -5
Lim h--> 0 [-5] = -5

Answer 2

The limit must be applied in other functions. Here it is not necessary because the function is a line. The tangent line to a line is the own line. That is: the tangent line to f(x) = 3-5x, in whatever point is just f(x) = 3 - 5x.