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# If a , b , and c are consecutive odd integers, which express

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If a , b , and c are consecutive odd integers, which express [#permalink]  09 Nov 2017, 07:16
Expert's post
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Question Stats:

72% (00:47) correct 27% (00:46) wrong based on 18 sessions

If a, b, and c are consecutive odd integers, which expression must be odd?

Choose $$all$$ that apply.

❑ $$a*(b+c)$$

❑ $$(a+b) - c$$

❑ $$a*b*c$$

❑ $$2*(c-a) + b$$

❑ $$a + b + c$$
[Reveal] Spoiler: OA

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Re: If a , b , and c are consecutive odd integers, which express [#permalink]  09 Nov 2017, 08:30
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Let's check them one by one

❑ $$a*(b+c)$$ -> odd+odd = even, odd*even = even, so it must be even

❑ $$(a+b) - c$$ -> odd+odd = odd, odd-odd = odd, so it must be odd

❑ $$a*b*c$$ -> odd*odd = odd, so it must be odd

❑ $$2*(c-a) + b$$ -> odd-odd = odd, even*odd = even, even+odd = odd, so it must be odd

❑ $$a + b + c$$ -> odd+odd = even, even+odd = odd, so it must be odd

Then, the answers are B, C, D, E.
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Re: If a , b , and c are consecutive odd integers, which express [#permalink]  22 Jan 2019, 07:13
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Expert's post
Carcass wrote:

If a, b, and c are consecutive odd integers, which expression must be odd?

Choose $$all$$ that apply.

A) $$a*(b+c)$$

B) $$(a+b) - c$$

C) $$a*b*c$$

D) $$2*(c-a) + b$$

E) $$a + b + c$$

To solve this question, we can EITHER apply the rules for ODDS and EVENS (as IlCreatore has done) or we can plug in 3 consecutive ODD integers for a, b and c
How about a = 1, b = 3 and c = 3

We get:

A) $$1*(3+5) = 8$$, which is EVEN. ELIMINATE.

B) $$(1+3) - 5 = -1$$, which is ODD. KEEP!

C) $$1*3*5 = 15$$, which is ODD. KEEP!

D) $$2*(5-1) + 3 = 11$$, which is ODD. KEEP!

E) $$1 + 3 + 5 = 9$$, which is ODD. KEEP!

Cheers,
Brent
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Brent Hanneson – Creator of greenlighttestprep.com

Re: If a , b , and c are consecutive odd integers, which express   [#permalink] 22 Jan 2019, 07:13
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