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JHTIPU18
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If x and y are two distinct positive integers divisible by 4, then whi Updated on: 19 Jan 2021, 13:22
Originally posted by JHTIPU18 on 19 Jan 2021, 13:18.
Last edited by Bunuel on 19 Jan 2021, 13:22, edited 1 time in total.
Renamed the topic, edited the question and added the OA.
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C
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25% (medium)

Question Stats:

77% (01:26) correct 23% (01:37) wrong based on 214 sessions

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If x and y are two distinct positive integers divisible by 4, then which of the following is necessarily divisible by 8?

(A) x + y
(B) x - y
(C) x^2 + y^2
(D) 2x + y
(E) none of these
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C
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TestPrepUnlimited
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GMAT 1: 780 Q51 V45
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If x and y are two distinct positive integers divisible by 4, then whi 19 Jan 2021, 16:10
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JHTIPU18
If x and y are two distinct positive integers divisible by 4, then which of the following is necessarily divisible by 8?

(A) x + y
(B) x - y
(C) x^2 + y^2
(D) 2x + y
(E) none of these
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We may let \(x = 4*i\) and \(y = 4*j\) to help us with this question, where i and j represent any positive integers. We want the answer to be a multiple of 8 so we plug these in to check which of them must be a multiple of 8.

(A), (B) are both multiples of 4 but not necessarily a multiple of 8.
(C) is \(16i^2 + 16j^2\) which is a multiple of 8.
(D) is close but \(8i + 4j\) only guarantees a factor of 4.

Ans: C
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Sagacious37317
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If x and y are two distinct positive integers divisible by 4, then whi 10 Sep 2022, 21:49
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I dont get why (A) are both multiples of 4 but not necessarily a multiple of 8. if x=4 and y= 4 then x+y =8.
how to scan between c and a?
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syedismailali1998
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If x and y are two distinct positive integers divisible by 4, then whi 02 Oct 2022, 04:20
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Sagacious37317
I dont get why (A) are both multiples of 4 but not necessarily a multiple of 8. if x=4 and y= 4 then x+y =8.
how to scan between c and a?
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The primary issue with x+y is let's take an example

4*x + 4*y

Now assume x=1 & y=6

4*(1) + 4*(6) = 28 (Not a multiple of 8), same goes with option B, hence we eliminated A & B as it doesn't guarantee a multiple of it.

In case of C, as it is squared, the multiple of 8 is guaranteed.

Hope this helps
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If x and y are two distinct positive integers divisible by 4, then whi 17 Aug 2025, 04:10
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