(x+y)(x^2-y^2)=0 which of the following must be true?

Test Preparation
1

<p>(a)x=y
(b)x=-y
(c)x^2=y^2
, i found all these answers appear to be correct;however, the correct answer is c.</p>

2

<p>Either x=y, or x=-y. In either case, x^2=y^2, so (c) must be true irregardless.</p>

3

<p>JW, is this an SAT question, or is it one from the ACT?</p>

4

<p>x = y, or x = -y. This means that (a) does not necessarily have to be true, same with (b). However x^2 does equal y^2, so the answer is (c).</p>