SAT Math Question of the Day

Q: If (2 - x)(2 + x) = -5, then what is a possible answer for x?

1. 1
2. 2
3. 3
4. 4
5. 5

UNANSWERED.

The correct answer is C.

A:

One way to do this problem is to just plug in the possible answers and see which one fits the equation.

Let's try choice A, where x is 1,
(2 - x)(2 + x) = -5
(2 - 1)(2 + 1) = -5
(1)(3) = -5
3 = -5
Nope, choice A doesn't work. Onto choice B, x is 2 ...
(2 - x)(2 + x) = -5
(2 - 2)(2 + 2) = -5
(0)(4) = -5
0 = -5
Still not a match. Let's try choice C, where x is 3 ...
(2 - x)(2 + x) = -5
(2 - 3)(2 + 3) = -5
(-1)(5) = -5
-5 = -5
IT WORKS!
So the answer is x is 3 or choice C.

Another way to solve it is algebraically:
(2 - x)(2 + x) = -5
(x - 2)(x + 2) = 5
x² - 4 = 5
x² = 9
x = 3 or -3
So, C is the correct answer.