SOLUTION: If (x-y)^2 = 71 and x^2 + y^2 = 59, what is the value of xy?

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Question 1087016: If (x-y)^2 = 71 and x^2 + y^2 = 59, what is the value of xy?
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
.
%28x-y%29%5E2 = 71 = x%5E2+-+2xy+%2B+y%5E2 = %28x%5E2+%2B+y%5E2%29 - 2xy = 59 - 2xy  ====+

-2xy = 71 - 59 = 12  ====>  xy = 12%2F%28-2%29 = -6.

Solved.