LUANDATO wrote:If x^2 + 5x = 0, what is the value of x·y?
(1) y^2 − 25 = 0
(2) x^2 − 10x = 0
The OA is B.
Can any expert explain this DS question please? I need help to solve it.
We have x^2 + 5x = 0.
=> x(x + 5) = 0 => x = 0 or -5.
(1) y^2 − 25 = 0
=> y = ±5.
Case 1: If x = 0, then x.y = 0.
Case 2: If x = -5, then x.y = -5.(±5) = ±25.
No unique answer. Insufficient.
(2) x^2 − 10x = 0
x(x - 10) = 0 => x = 0 or 10
Since from the question, we know that x = 0 or -5 and from Statement 2, we know that x = 0 or 10, thus, x = 0.
Since x = 0, the value of x.y = 0 irrespective of the value of y. Sufficient.
The correct answer:
B
Hope this helps!
-Jay
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