If I interpret your question correctly, it should read:duongthang wrote:Is square of X + Square of Y is bigger than 6
1, square of (x+y) is bigger than 6
2, xy =2
I do not know how to write "square" inhere. pls, help
Is x^2 + y^2 > 6 ?
(1) (x+y)^2 > 6
(2) xy =2
Statement 1:
(x + y)^2 > 6
x^2 + 2xy + y^2 > 6
We don't know anything about 2xy. Hence insufficient.
Statement 2:
xy = 2
if x = 4, y = 0.5, then x^2 + y^2 > 6. YES
if x=2, y=1, then x^2 + y^2 <6. NO
Insuffcient.
Both statements together:
x^2 + 2xy + y^2 > 6
x^2 + 2(2) + y^2 > 6
x^2 + y^2 > 2
we can only guarantee that x^2 + y^2 is greater than 2. But we cannot conclude anything about it being greater than 6. Insufficient.
Choose E.
-BM-
