Question

Let f(x) = 4x + 3 and g(x) = -2x + 5. Find (f.g)(5)

Answer 1

Answer:
`(f*g)(5)=-115`

Explanation:

Given the function f(x):

`f(x) = 4x + 3`

And the function g(x):

`g(x) = -2x + 5`

We need to multiply them in order to find
`(f*g)(x)`. Then:

`(f*g)(x) = (4x + 3)(-2x + 5)\\(f*g)(x)=-8x^2+20x-6x+15\\(f*g)(x)=-8x^2+14x+15`

Now we must substitute
`x=5` into
`(f*g)(x)=-8x^2+14x+15`. Then, we get that
`(f*g)(5)` is:

`(f*g)(5)=-8(5)^2+14(5)+15\\(f*g)(5)=-115`