X and Y

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X and Y

by goyalsau » Fri Oct 08, 2010 4:26 am
Is x2 > 4x - 3y?

(1) y > 0 and x > 4

(2) 4x - 3y = -1
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by kmittal82 » Fri Oct 08, 2010 4:57 am
Stmt1)

x > 4, y > 0

According to the equation, the bigger y is, the lesser the "-3y" quantity becomes, and for x>4, x^2 will always be greater than 4x

Sufficient

stmt2)

4x - 3y = -1, so the question is asking is x^2 > -1. Sqaure of any number is greater than -1, so sufficient.

So, in my opinion, it should be (D)

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by Rahul@gurome » Fri Oct 08, 2010 5:04 am
(1) If x = 5 and y = 1, then x^2 = 25 and 4x - 3y = 17; here x^2 > 4x - 3y.
If x = 5 and y = 10, then x^2 = 25 and 4x - 3y = -10; here x^2 > 4x - 3y.
Similarly, we can see that for various values of x, x^2 > 4x - 3y.
So, (1) is SUFFICIENT.

(2) x^2 will always be positive and 4x - 3y = -1. So, x^2 > 4x - 3y
So, (2) is SUFFICIENT.
[spoiler]
The correct answer is (D).[/spoiler]
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by sanju09 » Fri Oct 08, 2010 5:05 am
goyalsau wrote:Is x2 > 4x - 3y?

(1) y > 0 and x > 4

(2) 4x - 3y = -1

D
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