f xy = 3, what is the value of xy(x + y) ?
(1) x – y = 2
(2) x^2 + y^2 = 10
1) x - y = 2
xy = 3
x and y will have two values
Insuff
2. (x+y)2 -2xy = 10
x+y = +- 4
insuff.
hence IMO E
Cramya DS 2
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
-
ronniecoleman
- Legendary Member
- Posts: 546
- Joined: Sun Nov 16, 2008 11:00 pm
- Location: New Delhi , India
- Thanked: 13 times
-
acecoolan
- Master | Next Rank: 500 Posts
- Posts: 139
- Joined: Wed May 07, 2008 12:27 pm
- Thanked: 8 times
E
Almost fell into the trap with 2
1) x-y = 2
solving this in combination with xy =3, you get a quadratic which can have 2 sets of soultions
Insuff
2) x^2 + y^2 = 10
(x+y)^2 = x^2 + y^2 + 2(xy)
= 10 + 6
= 16
hence (x + y) = +- 4
Insuff
Hence E)
Almost fell into the trap with 2
1) x-y = 2
solving this in combination with xy =3, you get a quadratic which can have 2 sets of soultions
Insuff
2) x^2 + y^2 = 10
(x+y)^2 = x^2 + y^2 + 2(xy)
= 10 + 6
= 16
hence (x + y) = +- 4
Insuff
Hence E)
