SOLUTION: if x+y=7*2 and xy =5*2 find x-y

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Question 762650: if x+y=7*2 and xy =5*2 find x-y
Answer by tommyt3rd(5050) About Me  (Show Source):
You can put this solution on YOUR website!
%0D%0A%28x-y%29%5E2+=+x%5E2+-+2+xy+%2B+y%5E2%0D%0A
%0D%0A%28x%2By%29%5E2+=+x%5E2+%2B+2+xy+%2B+y%5E2%0D%0A
subtracting...
%0D%0A%28x-y%29%5E2-%28x%2By%29%5E2+=+-4xy+%0D%0A
and so...

%0D%0A%28x-y%29%5E2+=%28x%2By%29%5E2+-4xy+=+%2814%2B10%29%5E2-4%2814%29%2810%29=16%0D%0A
So x-y=4


:)