Question

If f(x) = x2 − 2x + 9 and g(x) = 8 − x, what is (f o g)(−4)? A. 111 B. 144 C. 120 D. 129

Answer 1

Answer: OPTION D

Step-by-step explanation:

Given the functions $f(x) = x^2 - 2x + 9$ and  $g(x) = 8 - x$, you need to substitute the function g(x) into the function f(x), then:

$(fog)(x)=(8-x)^2 - 2(8-x) + 9$

Now, you need substitute the input value $x=-4$ into $(fog)(x)$, then you get the following output value:

 $(fog)(-4)=(8-(-4))^2 - 2(8-(-4)) + 9$

 $(fog)(x)=(8+4)^2 - 2(8+4) + 9$

 $(fog)(x)=(12)^2 - 2(12) + 9$

 $(fog)(x)=129$

This matchis with the option D