3x+2y<18?

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3x+2y<18?

by neoreaves » Sat May 08, 2010 8:50 am
If x/y >2, is 3x+2y<18?

1. x-y is less than 2
2. y-x is less than 2

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by iamseer » Sat May 08, 2010 1:13 pm
x/y>2 therefore x,y are both negative or both positive. Also, neither is equal to 0.

from 1:
x-y<2
If x and y are both negative, irrespective of difference between them, 3x+2y<0 and hence <18
if x and y are both positive, x>2y
So, 2y<x<y+2
2y<y+2, y<2 therefore x<4
If y<2 and x<4 then 3x+2y<16
Sufficient

from 2:
y-x<2
again,
If x and y are both negative, irrespective of difference between them, 3x+2y<0 and hence <18
if x and y are both positive, x>2y
So, x>2y and x>y+2
2x>3y+2
x>1.5y+1
y can take any value >0
Not Sufficient

IMO A

Let us know OA.
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