[email protected] wrote:What is the value of p³ − q³?
(1) p − q = 0
(2) p + q = 0
Target question: What is the value of p³ − q³?
This question requires you to know how to factor a DIFFERENCE OF CUBES (which is not required on the GMAT).
The factoring is as follows:
a³ - b³ = (a - b)(a² + ab + b²)
So, we can REPHRASE the target question as follows:
REPHRASED target question: What is the value of (p - q)(p² + pq + q²)?
Statement 1: p − q = 0
If
p - q = 0, then
(p - q)(p² + pq + q²) = (0)(p² + pq + q²) = 0
Since we can answer the
REPHRASED target question with certainty, statement 1 is SUFFICIENT
Statement 2: p + q = 0
There are several values of p and q that satisfy this condition. Here are two:
Case a: p = 0 and q = 0, in which case
p³ − q³ = 0
Case b: p = 1 and q = -1, in which case
p³ − q³ = 2
Since we cannot answer the
target question with certainty, statement 2 is NOT SUFFICIENT
Answer =
A
Cheers,
Brent
