If x is an even integer, which of the following is an odd integer?

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Re: If x is an even integer, which of the following is an odd integer?

by [email protected] » Tue Mar 31, 2020 3:15 pm

Hi All,

We're told that X is an EVEN integer. We're asked which of the following is an ODD integer? This question can be solved with Number Properties or TESTing VALUES.

IF... X = 2, then the answer become....

(A) 3x + 2 = 3(2) + 2 = 6+2 = 8 NOT Odd
(B) 7x = 7(2) = 14 NOT Odd
(C) 8x +5 = 8(2) + 5 = 21 This IS Odd
(D) x^2 = (2)^2 = 4 NOT Odd
(E) x^3 = (2)^3 = 8 NOT Odd

Final Answer: C

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Rich

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Re: If x is an even integer, which of the following is an odd integer?

by Brent@GMATPrepNow » Wed Apr 01, 2020 4:36 am

BTGModeratorVI wrote: ↑
Tue Mar 31, 2020 5:11 am
If x is an even integer, which of the following is an odd integer?

(A) 3x + 2
(B) 7x
(C) 8x +5
(D) x^2
(E) x^3

Answer: C
Source: Official guide

With questions like this, we can apply RULES related to odds and evens (as skywalker18 did), or we can just PLUG IN an even value for x.
The easiest value to plug in is 0

(A) 3(0) + 2 = 2 EVEN - ELIMINATE A
(B) 7(0) = 0 EVEN - ELIMINATE B
(C) 8(0) +5 = 5 ODD. DONE!!!
Answer: C

For "kicks" let's keep going (although, on test day, we would select C and move onto the next question.

(D) 0^2 = 0 EVEN - ELIMINATE D
(E) 0^3 = 0 EVEN - ELIMINATE E

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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Re: If x is an even integer, which of the following is an odd integer?

by Scott@TargetTestPrep » Wed Apr 01, 2020 4:21 pm

BTGModeratorVI wrote: ↑
Tue Mar 31, 2020 5:11 am
If x is an even integer, which of the following is an odd integer?

(A) 3x + 2
(B) 7x
(C) 8x +5
(D) x^2
(E) x^3

Answer: C
Source: Official guide

If x is an even integer, then kx and x^k (where k is a positive integer) will also be even. We can eliminate choices B, D, and E. Since even + even = even, and even + odd = odd, we see that choice A is even and choice C is odd. Thus, choice C is the correct answer.

Answer: C

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