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x²-y² = y²+2y+4-y²=2*(y+2)
thus x²-y² should be a multiple of 2=> 2*(y+2) = 36 or 40 or 80
when x²-y²= 2*(y+2)=36 => y=16 and x=18 reject this answer
when x²-y²= 2*(y+2)=40 => y=18 and x=20 reject this answer
when x²-y²=2*(y+2)=80 => y=38 and x=40 correct answer
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I got x=21,

If x=21, then y=19 and x^2 - y^2 = 80
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goodyear2013
For integers, \(x\) and \(y, x=y+2.\) From the table below, select the values that could correspond to \(x\) and \(x^2 − y^2.\)

Given : x=y+2 ----> y = x-2
To find : x & (x^2 - y^2).

How can you solve it it in a faster way ?

Bring it in terms of X. Why ? Because , we have to find the value of x and we are given answer choices for value of x.
So,
(x^2 - y^2) = [x^2] - [(x-2)^2] = [x^2] - [x^2 + 4 - 4x] = x^2 - x^2 - 4 + 4x = 4x -4

Therefore, (x^2 - y^2) = 4x-4

Now as soon as you put , x=21 , 4x-4 = (21*4) - 4 = 80.

Hence , 21 and 80 are the answers respectively for x & (x^2 - y^2).

Hope it helps.
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