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If a = 1 and b = -2, then (2a^2 + b)(x + y) + (a + b)(x - y) =
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23 Jul 2016, 14:19
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89% (00:58) correct
If \(a = 1\) and \(b = -2\), then \((2a^2 + b)(x + y) + (a + b)(x - y) =\)
(A) 0
(B) 2x
(C) y - x
(D) x - y
(E) x + y
(A) 0
(B) 2x
(C) y - x
(D) x - y
(E) x + y
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Joined: 11 Oct 2015
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Given Kudos: 38
Schools: HBS 2+2 '22 MIT Sloan MSMS"18
GMAT 1: 730 Q49 V40
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Re: If a = 1 and b = -2, then (2a^2 + b)(x + y) + (a + b)(x - y) =
[#permalink]
23 Jul 2016, 16:12
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\(\left( 2a^{2\; }+\; b \right)\left( x+y \right)\; +\; \left( a\; +\; b \right)\left( x\; -\; y \right)\;\)
\(=\; \left( 2-2 \right)\left( x+y \right)\; -1\left( x-y \right)\;\)
\(=\; o\left( x+y \right)\; -\; x+y\;\)
\(=\; y-x\)
\(Answer\; \mbox{C}\)
Is it really from Gmatprep? It's really strange that they didn't put the x - 3y choice.
That choice would have probably been the most common mistake on this question.
\(=\; \left( 2-2 \right)\left( x+y \right)\; -1\left( x-y \right)\;\)
\(=\; o\left( x+y \right)\; -\; x+y\;\)
\(=\; y-x\)
\(Answer\; \mbox{C}\)
Is it really from Gmatprep? It's really strange that they didn't put the x - 3y choice.
That choice would have probably been the most common mistake on this question.
General Discussion
Re: If a = 1 and b = -2, then (2a^2 + b)(x + y) + (a + b)(x - y) =
[#permalink]
29 Jul 2016, 15:14
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Putting A=1 and B = -2 => 2A^2-B=0 ; so the first part of the term is zero
with second term => (1-2) *(x+y)=y-x => Smash C
with second term => (1-2) *(x+y)=y-x => Smash C