Question

Find f(3).

f(x) = x2 + 5x - 9
A) 7
B) 10
C) 9
D) 15

Answer 1

f(3) = 15. Correct: D)

Step-by-step explanation:

Numeric Value of a Function

The value of a function f(x) when x = a is calculated by replacing the x for a. We have the function:

`f(x)=x^2+5x-9`

It is required to find f(3), or the numeric value of f when x=3. Replace x for 3

`f(3)=3^2+5(3)-9`

`f(3)=9+15-9`

`f(3)=15`

A) Incorrect. f(3) is not 7

B) Incorrect. f(3) is not 10

C) Incorrect. f(3) is not 9

D) Correct. f(3) =15 as found above.