Target question: What is the value of |x|?Sh_QR wrote: 1.What is the value of |x| ?
A) x = -|x|
B) x² = 4
Statement 1: x = -|x|
This statement doesn't FEEL sufficient, so I'm going to TEST some values.
There are several values of x satisfy statement 1. Here are two:
Case a: x = 0, (since 0 = -|0|). In this case, |x| = |0| = 0
Case b: x = -1, (since -1 = -|1|). In this case, |x| = |-1| = 1
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT
Aside: For more on this idea of plugging in values when a statement doesn't feel sufficient, you can read my article: https://www.gmatprepnow.com/articles/dat ... lug-values
Statement 2: x² = 4
There are two solutions to this equation: x = -2 and x = 2
However, this does not mean that the statement is insufficient, because the question is not asking us to find the value of x. We're asked to find the value of |x|, and in both cases, we get the SAME ANSWER
Case a: x = -2. In this case, |x| = |-2| = 2
Case b: x = 2. In this case, |x| = |2| = 2
So, we can be CERTAIN that |x| = 2
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer = B
Cheers,
Brent
