Question

What are the x-intercepts of the function f(x)=(x + 1)(x + 4)?

A) (0, 5)
B) (-4,0) and (-1,0)
C) (4,0) and (−3,0)
D) (4,0) and (1,0)

Answer 1

B because x =-1 and -4 make f(x)=0

Answer 2

B

Explanation:

To find the x- intercepts let f(x) = 0 , that is

(x + 1)(x + 4) = 0

Equate each factor to zero and solve for x

x + 4 = 0 ⇒ x = - 4

x + 1 = 0 ⇒ x = - 1

The x- intercepts are (- 4, 0 ) and (- 1, 0 )