
Question: If \(x\neq 0\) ,what is the value of x?
“If ,what is the value of x?”– is a topic of the GMAT Quantitative reasoning section of GMAT. This question has been taken from the book "GMAT Quantitative Review". GMAT Quant section consists of a total of 31 questions. GMAT Data Sufficiency questions consist of a problem statement followed by two factual statements. GMAT data sufficiency comprises 15 questions which are two-fifths of the total 31 GMAT quant questions.
Solution and Explanation:
Approach Solution 1:
(1) The distance between x and –x on the number line is equal to the distance between \(x^2\) and \(-x^2\)
The distance between a and b on the number line is |a-b|. Thus, the statement above means |x – (-x)| = | \(x^2\)-(\(-x^2\))|
|2x| = |\(2x^2\)|
|2x| = |2x| * |x|
Reduce by |2x| (note here that we can safely do that since |2x| \(\neq\)0. We are told x 0, thus |2x| \(\neq\)0):
1 = |x|
X can be 1 or -1.
Hence not sufficient.
(2) x ? |x| = 0, where ? represents one of the three operations addition, subtraction or multiplication
If ? is addition we’d have x + |x| = 0, which is true for all non-positive values of x.
If ? is subtraction we’d have x - |x| = 0, which is true for all non-negative values of x.
If ? is multiplication we’d have x * |x| = 0, which is true when x = 0 but since we are told that x \(\neq\)0, then ? cannot be multiplication.
Not sufficient
(1) + (2) If ? is subtraction then x = 1 (from (1)) but if ? is addition then x = -1 (from (1)).
Not sufficient
Correct Answer: E
Approach Solution 2:
(1) x can take 0 or 1 or -1
In all cases the distance between x and –x on the number line is equal to the distance between \(x^2\) and \(-x^2\)
Not sufficient
(2) If x = 0 then ? represents any one of the operations
If x = 0 then ? represents any one of the operations.
If x = -1 then ? represents addition
If x = 1 then ? represents subtraction
Not sufficient
On combining also not sufficient
Correct Answer: E
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