Question

Which value of a would make the following expression completely factored

x^2-a

A)12
B)36
C)49
D)81

Answer 1

So I just did the problem and im pretty sure the answer is A

Answer 2

A)

Explanation:

We know that the expression (x^2 - a^2) can be written as (x-a)(x+a). So an expression of this type: (x^2 - a^2) wouldn't be completely factored because it could be factorized even more.

So we know that 36 = 6^2, 49= 7^2 and 81 = 9^2. So if we choose any of these options (Option B, C and D) it wouldn't be completely factored.

The correct is the option A, given that if a=12, it wouldn't be a perfect square, so it would be completely factored.