briandoldan wrote:

Is it Ok to take the roots first?For example, in question 1 the roots for statement 1 are 0 and 5. For statement II, 0 and -5

Data sufficiency

1) Is X=5?

(I) \(x^2\) – 5x = 0

(II)\(2x^2\) + 10x= 0

2) Is x = y?

(I) |x-2|= 5

(II) \(y^2\) – 4y – 21=0

I'm not sure that I understand your question... But as for the problems:

Is x=5?

(1) \(x^2-5x=0\) --> \(x=0\)

OR \(x=5\). Not sufficient, to answer whether \(x=5\).

(2) \(2x^2+10x=0\) --> \(x=0\)

OR \(x=-5\). Here we know that \(x\neq{5}\), hence sufficient.

Answer: B.

Is x = y?(1) \(|x-2|= 5\). Clearly insufficient as no info about \(y\). But from this statement we know that either \(x=7\) or \(x=-3\).

(2) \(y^2-4y-21=0\). Clearly insufficient as no info about \(x\). But from this statement we know that either \(y=7\) or \(y=-3\).

(1)+(2) Now, it's possible that

both \(x\) and \(y\) equal to -3 (or 7) and in this case answer would be YES: \(x=y\) BUT it's also possible \(x\) to be -3 and \(y\) to be 7 (or vise-versa) and in this case answer would be NO: \(x\neq{y}\). Two different answers to the question, hence not sufficient.

Answer: E.

Hope it helps.

Thanks a lot Bunuel. It helped a lot. =)