Re: If k is a positive integer, is the value of x y less than half the va

Published: 29/05/2017
Re: If k is a positive integer, is the value of x y less than half the va
Source: GMATCLUB.COM

ankitsaroha wrote: Clearly, k=2 alone is insufficient as we know nothing of x and y. Therefore, B and D choices are gone. Let us take z = 3^k - 2^k If x = 3^(k - 1) and y = 2^(k - 1) then x - y = 3^k/3 - 2^k/2 = (2.3^k - 3.2^k)/6 = (2.3^k - 2.2^k - 1.2^k)/6 = 2(3^k - 2^k - 2^(k - 1))/6 = (3^k - 2^k - 2^(k - 1))/3 = (z - 2^(k - 1))/3 Since, 2^(k - 1) > 0, we get (x - y) < z. Therefore, 1st st

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