If x2 - y2 = -12 and x + y = 6, find x and y. Choose the correct choice from the following answers.
A) x = 2 , y = 4	B) x = 3 , y = 5	C) x = 4 , y = 6	D) x = 5 , y = 7	E) x = 6 , y = 8
x2 - y2 = (x - y)(x + y) = -12 : given   6(x - y) = -12 : substitute x + y by 6   (x - y) = -2 : solve for x - y   (x - y) = -2 and x + y = 6 : 2 by 2 system.   x = 2 , y = 4 : solve above system.   correct answer x = 2 , y = 4
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If x2 - y2 = -12 and x + y = 6, find x and y.