Question

question 8 of 10
which of the following is an x-intercept of the function,
$f(x) = x^3 + 3x^2 - 10x - 24$
a. 2
b. -3
c. -4
d. 4

Explanation:

Step1: Test x=2 in f(x)

$f(2)=2^3+3(2)^2-10(2)-24=8+12-20-24=-24≠0$

Step2: Test x=-3 in f(x)

$f(-3)=(-3)^3+3(-3)^2-10(-3)-24=-27+27+30-24=6≠0$

Step3: Test x=-4 in f(x)

$f(-4)=(-4)^3+3(-4)^2-10(-4)-24=-64+48+40-24=0$

Step4: Test x=4 in f(x)

$f(4)=4^3+3(4)^2-10(4)-24=64+48-40-24=48≠0$

Answer:

C. -4