Question

question 40
which of the following is a root of the function f(x)=x^2 + 7x + 12?
select one
-3
-6
4
3

Explanation:

Step1: Recall root definition

A root of a function \( f(x) \) is a value \( x \) such that \( f(x) = 0 \). So we need to check which of the given options makes \( f(x)=x^2 + 7x + 12 = 0 \).

Step2: Test \( x=-3 \)

Substitute \( x = -3 \) into \( f(x) \):
\( f(-3)=(-3)^2 + 7(-3)+12 = 9 - 21 + 12 = 0 \).

Step3: Verify other options (optional, but confirm)

• For \( x=-6 \): \( f(-6)=(-6)^2 + 7(-6)+12 = 36 - 42 + 12 = 6

eq 0 \).

• For \( x=4 \): \( f(4)=4^2 + 7(4)+12 = 16 + 28 + 12 = 56

eq 0 \).

• For \( x=3 \): \( f(3)=3^2 + 7(3)+12 = 9 + 21 + 12 = 42

eq 0 \).

Answer:

-3 (the option with -3)