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If r and s are integers and rs + r is odd, which of the following must [#permalink]
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01 Jun 2007, 23:57
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If r and s are integers and rs + r is odd, which of the following must be even ? A. R B. s C. r + s D. rs  r E. r^2 + s
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Last edited by Bunuel on 04 Oct 2014, 14:08, edited 1 time in total.
Renamed the topic, edited the question and added the OA.



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Re: If r and s are integers and rs + r is odd, which of the following must [#permalink]
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02 Jun 2007, 11:55
Himalayan is right !
according to OG , zero is even
R*S+R =
e=even
o=odd
we have two options:
(1) e*o+e = e
(2) o*e+o = o
since the stem states that R*S+R =odd then we will choose (2) and S must be even.



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Re: If r and s are integers and rs + r is odd, which of the following must [#permalink]
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02 Jun 2007, 15:43
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RS+R = R(S+1) > which is ODD
Now this implies that R is odd AND S+1 is odd. which means S is even
Ans B.



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Re: If r and s are integers and rs + r is odd, which of the following must [#permalink]
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04 Oct 2014, 13:02
bsd_lover wrote: RS+R = R(S+1) > which is ODD Now this implies that R is odd AND S+1 is odd. which means S is even
Ans B. I am not sure if i got this one .. i mean if r is odd what is the possibility of s being odd or even ??



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If r and s are integers and rs + r is odd, which of the following must [#permalink]
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04 Oct 2014, 14:18
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Re: If r and s are integers and rs + r is odd, which of the following must [#permalink]
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04 Jun 2015, 05:02
Great explanation, Bunuel. Love your approach in every answer you put in the threads.



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Re: If r and s are integers and rs + r is odd, which of the following must [#permalink]
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04 Jun 2015, 16:46
Hi All, This question is perfect for TESTing VALUES. We're told that R and S are integers and that (R)(S)+R = ODD. We're asked which of the 5 answers MUST be even... IF.... R = 1 S = 2 (1)(2)+1 = 3 Answer A: R = 1 NOT even Answer B: S = 2 This IS EVEN Answer C: R+S = 3 NOT even Answer D: RSR = 21 = 1 NOT even Answer E: R^2+S = 1+2 = 3 NOT even Final Answer: GMAT assassins aren't born, they're made, Rich
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Re: If r and s are integers and rs + r is odd, which of the following must [#permalink]
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10 Jun 2015, 22:41
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If r and s are integers and rs + r is odd, which of the following must be even ?
If r is factored out to rewrite this as r (s + 1), we can see it as a product of two parts, r and s + 1. For their product to be odd, r must be odd and s + 1 must be odd. We also know that even + odd = odd. For s+1 to be odd, s must be even since 1 is odd. A. R B. s C. r + s D. rs  r E. r^2 + s



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Re: If r and s are integers and rs + r is odd, which of the following must [#permalink]
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29 Jul 2016, 23:56
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Re: If r and s are integers and rs + r is odd, which of the following must [#permalink]
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09 Sep 2017, 06:13
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