Question 885961: Please help me prove this equation: 2|x| |y| = x^2 + y^2
Answer by rothauserc(4718)   (Show Source):
You can put this solution on YOUR website! |x| > 0, |y|>0 for all x, y not = 0
if x = 0 or y = 0 then x = 0 and y = 0, trivial case
2|x| |y| = x^2 + y^2
note that |x||y| = |xy|
2|xy| = x^2 + y^2
x = y
2y^2 = y^2 + y^2
2y^2 = 2y^2
y^2 = y^2
y = y
same process for y = x
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