my soln was:
Case 1: WLOG |z| >= 1
Implies there can be no other number with |no| >1
So z = -x -y
implies
the expr is (x+y)^2 + x^2 + y^2 = 2(x^2 + y^2 + xy)
But |x| and |y| <=1
implies the expr <= 6
Case 2: | No number| > =1
Same proof :)
ie
the expr is (x+y)^2 + x^2 + y^2 = 2(x^2 + y^2 + xy)
But |x| and |y| <=1
implies the expr <= 6
Moderation Team
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