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nervousgmat
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If x and y are positive integers and 1 + x + y + xy = 15, 23 Jul 2007, 13:52
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If x and y are positive integers and 1 + x + y + xy = 15, what is the value of x + y?

A. 3
B. 5
C. 6
D. 8
E. 9

Please provide your explanations.



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If x and y are positive integers and 1 + x + y + xy = 15, 23 Jul 2007, 14:03
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isolate variables on the right so:

x+y+xy=14

only two numbers that fit this (2 and 4)

so isolating what it asks for (xy) we get answer D
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If x and y are positive integers and 1 + x + y + xy = 15, 23 Jul 2007, 14:17
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it should be C; its asking for X+Y (4+2)=6 :)
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zakk
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If x and y are positive integers and 1 + x + y + xy = 15, 23 Jul 2007, 14:43
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fresinha12
it should be C; its asking for X+Y (4+2)=6 :)


dang it. :oops: now would be a good time to state my RC isn't quite where I need it to be :lol:
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If x and y are positive integers and 1 + x + y + xy = 15, 23 Jul 2007, 14:48
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dang it me too :)
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If x and y are positive integers and 1 + x + y + xy = 15, 23 Jul 2007, 16:13
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The OA is C
Thanks, guys!
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If x and y are positive integers and 1 + x + y + xy = 15, 23 Jul 2007, 16:24
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1+x+y+xy = (1+x)(1+y) =15
3*5 = 15 => x,y = {2,4}

Ans : 6
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If x and y are positive integers and 1 + x + y + xy = 15, 23 Jul 2007, 19:25
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1+x+y+xy = (1+x) + y(1+x) = (1+x)(1+y) = 15

Cannot be (1,15) because x would not be positive
Must be (3,5), then x = 2, y = 4, then x+y = 6
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If x and y are positive integers and 1 + x + y + xy = 15, 23 Nov 2016, 10:51
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