Evaluate the function, find f(-2).

Question

Function: f(x) = 2x² + 3x

A. 2

B. -10

C. -14

D. -2

Answer 1

So, we take whatever is inside the parentheses and put it in place of x.

f(x) = 2x² + 3x

f(-2) = 2(-2)² + 3(-2)

f(-2) = 2(4) - 6

f(-2) = 8 - 6

f(-2) = 2

A

Note that 2x² means to multiply 2 times x². A common mistake is to multiply 2 times x and square the result.

2(-2)² ≠ (-4)²

Always square x and multiply by the coefficient, kinda in reverse order.

Answer 2

2(-2)^2 + 3(-2) =

2(4) + 3(-2) =

8 + -6

=2