SOLUTION: (x+y)2+(x-3y)2=

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Question 152567: (x+y)2+(x-3y)2=
Answer by orca(409) About Me  (Show Source):
You can put this solution on YOUR website!
First use the formula
%28a%2Bb%29%5E2=a%5E2%2B2ab%2Bb%5E2
and
%28a-b%29%5E2=a%5E2-2ab%2Bb%5E2
to expand,
then combine like terms.
%28x%2By%29%5E2%2B%28x-3y%29%5E2
= x%5E2%2B2xy%2By%5E2%2Bx%5E2-2x%2A%283y%29%2B%283y%29%5E2
= x%5E2%2B2xy%2By%5E2%2Bx%5E2-6xy%2B9y%5E2
= 2x%5E2-4xy%2B10y%5E2