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If r and s are integers and rs + r is odd, which of the foll
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17 Aug 2020, 11:14
17 Aug 2020, 11:14
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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
A. r
B. s
C. r + s
D. rs - r
E. r^2 + s
Re: If r and s are integers and rs + r is odd, which of the foll
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17 Aug 2020, 11:14
17 Aug 2020, 11:14
Expert Reply
Post A Detailed Correct Solution For The Above Questions And Get A Kudos.
Question From Our New Project: GRE Quant Challenge Questions Daily - NEW EDITION!
Question From Our New Project: GRE Quant Challenge Questions Daily - NEW EDITION!
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Re: If r and s are integers and rs + r is odd, which of the foll
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17 Aug 2020, 11:21
17 Aug 2020, 11:21
1
Carcass wrote:
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
A. r
B. s
C. r + s
D. rs - r
E. r^2 + s
Some important rules:
#1. ODD +/- ODD = EVEN
#2. ODD +/- EVEN = ODD
#3. EVEN +/- EVEN = EVEN
#4. (ODD)(ODD) = ODD
#5. (ODD)(EVEN) = EVEN
#6. (EVEN)(EVEN) = EVEN
Take: rs + r is odd
Factor: r(s + 1) is odd
If (r)(s + 1) = ODD, then from rule #4, we know that r is ODD and (s+1) is ODD
If s+1 is ODD, then it must be the case that s is even
Answer: B
Cheers,
Brent
