Question

Let `f(x) =7x+4` and g(x) = x-7 how do you find (fog)(x)?

Answer 1

`(f@g)(x) = f(g(x)) = 7(g(x)) + 4 = 7(x-7) + 4`

`= 7x-49+4 = 7x-45`

Explanation:

It may be less confusing to use different variables in the two function definitions.

For example:

`f(y) = 7y + 4`

`g(x) = x-7`

Then it is clear that we can let `y = g(x)` to find:

`(f@g)(x) = f(g(x)) = f(y) = 7y+4`

`= 7*g(x)+4 = 7(x-7)+4 = 7x-49+4 = 7x-45`