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Fri 28 Oct, 2011 07:35 am
Hello,
How does (a-b)^2 become (a+b)^2 - 4ab?
Please explain step by step
Thanks.
Andy Charles
@AndyCharles,
it doesn't
It becomes a^2 +b^2 - 2ab
@AndyCharles,
Expand (a+b)^2 and subtract 4ab. The answer is the expansion of (a-b)^2.
@markr,
True? It must have been late when I answered - when I did the working and it didn't come out right. Too much red wine.
@AndyCharles,
(a+b)^2-4ab= a^2+2ab+b^2-4ab=a^2-2ab+b^2=(a-b)^2