What is the value fo x^2 + y^2?
1) x^2 + y^2 = 2xy + 1
2) x^2 + y^2 = 4 - 2xy
Here's the answer OA is E
Here's my logic. [spoiler]I think it's C. It's clear that stem 1 is equal to (x-y)^2 = 1, and stem 2 is (x+y)^2 = 4. Each on its own is insufficient. But if you can solve for 2xy, then you know the answer. Setting the 2 equations equal to each other and solving for xy, which is equal to 3/4, and thus the answer to x^2 + y^2 = 2*3/4 + 1 = 4 - 2*3/4. What's wrong with this logic?
Please help...[/spoiler]
1) x^2 + y^2 = 2xy + 1
2) x^2 + y^2 = 4 - 2xy
Here's the answer OA is E
Here's my logic. [spoiler]I think it's C. It's clear that stem 1 is equal to (x-y)^2 = 1, and stem 2 is (x+y)^2 = 4. Each on its own is insufficient. But if you can solve for 2xy, then you know the answer. Setting the 2 equations equal to each other and solving for xy, which is equal to 3/4, and thus the answer to x^2 + y^2 = 2*3/4 + 1 = 4 - 2*3/4. What's wrong with this logic?
Please help...[/spoiler]
