Question

Which equations are true for x = –2 and x = 2? Check all that apply.

x2 – 4 = 0
x2 = –4
3x2 + 12 = 0
4x2 = 16
2(x – 2)2 = 0

Answer 1

A & D

Explanation:

I just took the test, the answers are A & D.

Answer 2

Only first and fourth equations are true for x = –2 and x = 2.

Explanation:

We have to check which equations are true for x = –2 and x = 2. Let us substitute these values in the given equations and see which equation satisfies the point.

(A)

For x= 2

`(2)^2-4=4-4=0`

For x= -2

`(-2)^2-4=4-4=0`

This equation is true for x = –2 and x = 2.

(B)

For x= 2

`(2)^2=4`

This equation is not true for x = –2 and x = 2.

(C)

For x= 2

`3(2)^2+12=12+12=24`

This equation is not true for x = –2 and x = 2.

(D)

For x= 2

`4(2)^2-16=16-16=0`

For x= -2

`4(-2)^2-16=16-16=0`

This equation is true for x = –2 and x = 2.

(E)

For x= 2

`2(2-2)^2=0`

For x= -2

`2(-2-2)^2=32`

Second point doesn't satisfy the equation.

Hence, this equation is not true for x = –2 and x = 2.

Therefore, only first and fourth equations are true for x = –2 and x = 2.