vivaslluis wrote:

Hi,

I have a doubt with the following question: - What is the value of x^3 - y^3 ?

(1) x^6 - y^6 = 0

(2) y = 0

I discard A, B and D because there's not enough information. I know the answer is C, but I don't get a clue of why.

Could someone help me with that?

Thank you!

So you need \(x^3 - y^3\).

Statement 1:\(x^6 - y^6 = (x^3 - y^3)(x^3+y^3) = 0\)

Insufficient, since either one of the two terms could be zero.

Statement 2:\(y^3 = 0\), which means \(x^3 - y^3 = x^3.\) Still insufficient.

Combining both, and substituting y = 0 in the second statement, we get : \(x^6 = 0\), which means \(x = 0\), and hence \(x^3 - y^3 = 0\)

Hence the answer is C.