Question

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

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