SOLUTION: Multiply (5a – 3b)^2

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Question 104673: Multiply (5a – 3b)^2
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
%285a-3b%29%5E2
%285a-3b%29%285a-3b%29
%285a%2B%28-3b%29%29%285a%2B%28-3b%29%29
Use the FOIL method (First, Outer, Inner, Last)
First %28highlight%285a%29+%2B+%28-3b%29%29+%28highlight%285a%29+%2B+%28-3b%29%29 : 5a%2A5a
Outer %28highlight%285a%29+%2B+%28-3b%29%29+%285a+%2B+highlight%28%28-3b%29%29%29 : 5a%2A%28-3b%29
Inner %285a+%2B+highlight%28-3b%29%29+%28highlight%285a%29+%2B%28-3b%29%29 : %28-3b%29%2A5a
Last %285a+%2B+highlight%28-3b%29%29+%285a+%2B+highlight%28%28-3b%29%29%29 :%28-3b%29%2A%28-3b%29
%285a-3b%29%5E2=First + Outer + Inner + Last
%285a-3b%29%5E2=5a%2A5a%2B5a%2A%28-3b%29%2B%28-3b%29%2A5a%2B%28-3b%29%2A%28-3b%29
%285a-3b%29%5E2=25a%5E2-15ab-15ab%2B9b%5E2
%285a-3b%29%5E2=25a%5E2-30ab%2B9b%5E2
A faster way is to compare to the following equation
%28X%2BY%29%5E2=X%5E2%2B2XY%2BY%5E2
where
X=5a and Y=-3b
%285a-3b%29%5E2=%285a%29%5E2%2B2%285a%29%28-3b%29%2B%28-3b%29%5E2
%285a-3b%29%5E2=25a%5E2-30ab%2B9b%5E2