Question

When solving this:
f(x) = 2x-5

[f(x+h)-f(x)]/h

Explain why I should get this:

[2(x+h) -5(2x-5)]/h

Rather than this:

[(2x-5+h) -(2x-5)]/h

I have seen the correct answer, but I want to know *WHY* it's supposed to turn out that way.

If I am putting X+H in wherever I see X, shouldn't it be the latter?

In [2(x+h) -5(2x-5)]/h, where is the (2x-5) after the -5 coming from?

Answer 1

f(x) = 2x-5

[f(x+h)-f(x)]/h <--- this what goes into the value of x in the function above

so
it goes into the value of x, for example if f(x) = x +5
then it would be
2(x+5) - 5

Answer 2

the -5 is coming from
f(x) = 2x -5
let's say for x = (x + h)
it would be
2(x+h) -5
do you understand it?..