Question

Given the function ƒ(x) = 8x^2 − 14x − 10, find ƒ(−2).

Answer 1

f(- 2) = 50

Explanation:

To evaluate f(- 2) substitute x = - 2 into f(x)

f(- 2) = 8(- 2)² - 14(- 2) - 10

= 8(4) + 28 - 10 = 32 + 28 - 10 = 50

Answer 2

f(-2) = 50

Explanation:

What f(-2) simply means is that you will substitute -2 in f(x) = 8x^2 − 14x − 10.

That is wherever you see x you replace it by 2

f(-2) = 8(-2)² - 14(-2) - 10

= 8(4) + 28 - 10 (note (-2)² = -2 × -2 = 4. Also, -14 × -2 = 28)

= 32 + 28 - 10

= 60 -10

=50

Therefore f(-2) = 50