Max@Math Revolution wrote:[GMAT math practice question]
$$If\ w^2x^3y^4z^5<0,is\ xyz>0?$$
1) x<0
2) y<0
w²x³y�z�<0 implies that w, x, y and z are all NONZERO, with the result that any even power of w, x, y and z will be POSITIVE.
Thus, we can safely divide w²x³y�z�<0 by any even power of w, x, y and z:
(w²x³y�z�)/(w²x²y�z�) < 0/(w²x²y�z�)
xz < 0.
Since xz<0, xyz>0 only if y is NEGATIVE.
Question stem, rephrased:
Is y<0?
Statement 1:
No information about y.
INSUFFICIENT.
Statement 2.
SUFFICIENT.
The correct answer is
B.
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