Question

If f(x) = 3x2 - 2x + 5, find f(-2)
A) -27
B) -11
C) -3
D) 21

Answer 1

Answer: D

Explanation:

f(x) = 3x2 - 2x + 5

f(-2) = 3*(-2)^2 - 2*(-2) + 5

f(-2) = 3*4 + 4 + 5

f(-2) = 12 + 4 + 5

f(-2) = 21

Answer 2

D

Explanation:

You have to be careful that you treat 21 as special. It is the only positive number. As you do the problem, keep an eye on 21.

f(-2) = 3x^2 - 2x + 5 Put -2 wherever you see an x

f(-2) = 3(-2)^2 - 2(-2) + 5 Calculate the first term.

f(-2) = 3(4) - 2(-2) + 5 Remove the brackets of the second term

f(-2) = 12 + 4 + 5 Combine

f(-2) = 21