139k views
0 votes
Given the function f(x)=(x+3)(4x2−1), find the x- and y-intercept(s).

1 Answer

2 votes

Answer: y-intercept = (0, -3)

x-intercepts: (-3,0), (1/2, 0) and (-1/2, 0)

Explanation:

An y-intercept occurs when x=0 and you get (0,y)

Plug x=0 into function:

f(x)=(x+3)(4x²−1)

f(0) = (0+3) (4(0)²-1)

f(0) = (3)(-1)

f(0)= -3

y-intercept = (0, -3)

An x-intercept occurs when y=0 and you get (x, 0)

f(x)=(x+3)(4x²−1)

0 =(x+3)(4x²−1) >set each parentheses =0 to solve for x

(x+3)=0 and (4x²−1)=0

x = -3 and 4x² = 1

x² = 1/4

x = ±(1/2)

There are 3 x-intercepts: (-3,0), (1/2, 0) and (-1/2, 0)

User Alex Karahanidi
by
7.9k points