LUANDATO wrote:Is the value of x less than 0?
(1) The product of x and y is negative.
(2) The difference between x and its reciprocal is positive.
The OA is E.
I don't understand this DS question. Please can any expert explain it for me? Thanks.
(1) The product of x and y is negative.
If x is negative and y is positive, the answer is Yes; however, if y is negative and x is positive, the answer is No. Insufficient.
(2) The difference between x and its reciprocal is positive.
x - 1/x > 0
=> x > 1/x
Case 1: Say x = -1/2, then 1/x = -2 and -1/2 > -2. The answer is yes, x is negative,
Case 2: Say x = 2, then 1/x = 1/2 and 2 > 1/2. The answer is no, x is NOT negative. Insufficient.
(1) and (2) combined:
Even after combing the two statements, we cannot conclude that x is negative or no.
The correct answer:
E
Hope this helps!
-Jay
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