SOLUTION: (2-sqrt7)^2= ? it says to simplify expression thanks for your help!

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Question 637292: (2-sqrt7)^2= ? it says to simplify expression thanks for your help!
Answer by jsmallt9(3758) About Me  (Show Source):
You can put this solution on YOUR website!
%282-sqrt%287%29%29%5E2
IMPORTANT: Exponents so not distribute! So simplifying this expression is not done by squaring the 2 and squaring the square root!!

To simplify this expression we can either use FOIL on %282-sqrt%287%29%29%282-sqrt%287%29%29 or use the %28a-b%29%5E2+=+a%5E2-2ab%2Bb%5E2 pattern.

I prefer using the pattern. With an "a" of "2" and a "b" of "sqrt%287%29", the pattern tells us that
%282-sqrt%287%29%29%5E2
would be
%282%29%5E2-2%282%29%28sqrt%287%29%29%2B%28sqrt%287%29%29%5E2
which simplifies as follows:
4+-+4sqrt%287%29+%2B+7
11+-+4sqrt%287%29