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Re: If a, b, and c are integers and abc ≠ 0, is a^2 – b^2 [#permalink]
11 Nov 2014, 03:26

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Re: If a, b, and c are integers and abc ≠ 0, is a2 – b2 a multiple of 4? [#permalink]
11 Dec 2014, 21:03

Question can be written as a^2 - b^2 or (a-b)*(a+b) is a multiple of 4 STAT1 alone is not sufficient as we don't know anything about b STAT2 alone is not sufficient as we don't know anything about a Taking both together

If c is odd then c-1 will be even and c*c-1 will be a multiple of 2 else if c i even then again c*c-1) will be a multiple of 2

So, in both the cases c*(c-1) is a multiple of 2. So, -2*(c^2)*((c-1)^2) will be a multiple of 4 (Actually will be a multiple of 8 too) So, Answer will be C

Hope it helps!

viktorija wrote:

If a, b, and c are integers and abc ≠ 0, is a^2 – b^2 a multiple of 4?

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