RobertP wrote:Hello everyone.
Is y^2 equal to xy?
(1) x^2 - y^2 = (x + 3)(y - 3)
(2) x = y
Statement 1:
If we substitute y=3 into x² - y² = (x + 3)(y - 3), we get:
x² - 3² = (x + 3)(3 - 3)
x² - 9 = (x + 3)(0)
x² - 9 = 0
x² = 9
x = ±3.
It's possible that x=3 and y=3.
In this case, y² = xy, and the answer to the question stem is YES.
It's possible that x=-3 and y=3.
In this case, y² ≠xy, and the answer to the question stem is NO.
Since the answer is YES in the first case but NO in the second case, INSUFFICIENT.
Statement 2:
Since y=x, xy = y*y = y².
Thus, y² = xy.
SUFFICIENT.
The correct answer is
B.
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