GMAT Question of the Day: Data Sufficiency

GMAT question of the day problem solving
Get Set for this GMAT Question of the Day: Problem Solving
December 22, 2014
GMAT question of the day sentence correction
GMAT Question of the Day: Sentence Correction
December 26, 2014
Show all

GMAT Question of the Day: Data Sufficiency

QOD2014_1224
Explanation
Before tackling the statement, simplify the complex expression in the question stem:

a2 − b2 = a2 − ab
-b2 = -ab
0 = b2 − ab
0 = b(b − a)

So either b or (b − a) = 0, but since b ≠ a, (b − a) ≠ 0. b = 0, so we look for a statment that connects c to b.

Statement (1) This statement connects c to a, which we know nothing about. It`s insufficient; the answer must be B, C, or E.

Statement (2) This statement does exactly what we want. c3 = 0 = c, so we can answer the question. This statement is sufficient.

The correct answer is B.