SOLUTION: (3a - 5)^2 =(3a)^2 + 5(3a)(-5)+ (-5)^2 =9^2 - 30a + 25 where in this equation does the 30a come from?

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: (3a - 5)^2 =(3a)^2 + 5(3a)(-5)+ (-5)^2 =9^2 - 30a + 25 where in this equation does the 30a come from?      Log On


   

Question 45514: (3a - 5)^2
=(3a)^2 + 5(3a)(-5)+ (-5)^2
=9^2 - 30a + 25
where in this equation does the 30a come from?
Answer by adamchapman(301) About Me  (Show Source):
You can put this solution on YOUR website!
%283a+-+5%29%5E2
%283a-5%29%283a-5%29
Use FOIL: (get the product of the firsts, then add the product of the outers, then add the product of the inners and then add the product of the lasts:)
%283a-5%29%283a-5%29=9a%5E2-15a-15a%2B25
The answer is:
9a%5E2-30a%2B25
I hope this helps.
Adam
P.S. please visit my website, I only set it up last week and it may be of use to you. The address is http://geocities.com/quibowibbler