Question

Suppose f(x) = 3x² + 8x - 9. Compute the following:

A.) f(-4) + f(5) =

B.) f(-4)-f(5)=

Answer 1

Answer: A. 113

B. -99

Explanation:

A.) f(-4) + f(5)=

3(-4)² + 8(-4) - 9 + 3(5)² + 8(5) - 9=

3(16) + (-32) - 9 + 3(25) + 40 - 9=

48 - 32 - 9 + 75 + 31 =

16 + 66 + 31=

82 + 31=113

B.) f(-4)-f(5)=

3(-4)² + 8(-4) - 9 - (3(5)² + 8(5) - 9)=

48 - 32 - 9 - (75 + 40 - 9)=

16 - 9 - 75 - 40 - (-9)=

7 - 115 + 9=

-108+9=-99