600 level question
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
-
clock60
- Legendary Member
- Posts: 759
- Joined: Mon Apr 26, 2010 10:15 am
- Thanked: 85 times
- Followed by:3 members
also got D, my thinking
is x^2>4x-3y
3y>4x-x^2
y>1/3*x(4-x)
let us review right part og the inequality
1/3*x(4-x), as 1/3>0 we can cancel it and left with
x(4-x)
it is +ve 0<x<4, and
-ve, x>4 and 0<x
so to estimate in relation to y we must know the sign of y
come to the st
(1) y>0 and x>4, if x>4 function x(4-x)=-ve and y=+ve
so y>x sufficient
(2)4x-3y=-1
simply insert in the problem
x^2 is always>=0
so x^2>=1 also sufficient
D is the answer
is x^2>4x-3y
3y>4x-x^2
y>1/3*x(4-x)
let us review right part og the inequality
1/3*x(4-x), as 1/3>0 we can cancel it and left with
x(4-x)
it is +ve 0<x<4, and
-ve, x>4 and 0<x
so to estimate in relation to y we must know the sign of y
come to the st
(1) y>0 and x>4, if x>4 function x(4-x)=-ve and y=+ve
so y>x sufficient
(2)4x-3y=-1
simply insert in the problem
x^2 is always>=0
so x^2>=1 also sufficient
D is the answer
-
sumanr84
- Legendary Member
- Posts: 758
- Joined: Sat Aug 29, 2009 9:32 pm
- Location: Bangalore,India
- Thanked: 67 times
- Followed by:2 members
shekar123 wrote:Is x2 > 4x - 3y?
(1) y > 0 and x > 4
(2) 4x - 3y = -1
St 1 : As y > 0, that means 3y > 0
when x>4, then ALWAYS --> x^2 > 4x
Since, we are subtracting further from 4x, and it will result in further lower value than 4x.
Thus , x^2 > 4x - 3y --> Sufficient
St 2: since 4x - 3y = -1, a -ve value, Therefore, x^2 ( which is always +ve) > 4x - 3y --> Sufficient
I am on a break !!
