Question

For the given functions f and g, find the indicated composition:

f(x) = 14x^2 - 10x, g(x) = 7x - 8
(f*g)(9)

HINT: the answer is 41,800 but I dont know how to show the work for it.

Answer 1

`f(x) = 14x^2 - 10x, g(x) = 7x - 8`

We need to find (fog)(x). Question says composition functions

(fog)(9)= f (g (9))

First we find g(9)

`g(x) = 7x - 8`

g(9)= 7(9) - 8 = 55

(fog)(9)= f (g (9))

Plug in 55 for g(9)

(fog)(9)= f (g (9)) = f(55)

Now we plug in 55 for x in f(x) and find f(55)

`f(x) = 14(55)^2 - 10(55) = 41800`

so (fog)(9) = 41,800