F(x) = 4x - 1; g(x) = 5x ( to the second power). which expression is equal to (f o g)(x)? a. 20x ( to the second power) - 1 b. 20x ( to the third power) - 5x ( to the second power) c. 5x ( to the second power) + 4x - 1 d. 80x ( to the second power) -40x + 5

(f o g)(x)=  

stick g(x) in for x in the function f(x)

(f o g)(x)= 4(g(x)) -1

               =4*5x^2 -1

            = 20x^2 -1

For this case we have that by definition, if we want to find (f o g) (x) we must replace g (x) in f (x), on the contrary, if we want to find (g o f) (x) we must replace f (x) in the function g (x).

So:

Thus, the expression that is equal to (f o g) (x) is, or 20x (to the second power) - 1

Option A

20x (to the second power) - 1