Question

(g of f)(-4) when f(x)=4x+5 and g(x)=4x^2 -5x-3

Answer 1

Answer:

(g o f)(- 4) = 570

Step-by-step explanation:

f(x)=4x+5

g(x)=4x² - 5x - 3

To find (g o f)(-4) we must first find

(g o f )(x)

To find (g of f)(x) substitute f(x) into g(x)

That's

(g o f)(x) = 4(4x + 5)² - 5(4x - 5) - 3

= 4( 16x² + 40x + 25) - 20x + 25 - 3

= 64x² + 160x + 100 - 20x + 22

(g o f)(x) = 64x² + 140x + 122

To find (g o f)(- 4) substitute the value of x that's - 4 into (g o f)(x)

Thats

(g o f)(- 4) = 64(-4)² + 140(-4) + 122

= 64(16) - 576 + 122

= 1024 - 454

We have the final answer as

(g o f)(- 4) = 570

Hope this helps you