SOLUTION: I am having trouble understanding how to do this problem. (3a-5)cubed I have the answer but don't know how they got it. Can you please help me????? Thanks, Jill

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I am having trouble understanding how to do this problem. (3a-5)cubed I have the answer but don't know how they got it. Can you please help me????? Thanks, Jill      Log On


   

Question 523083: I am having trouble understanding how to do this problem. (3a-5)cubed
I have the answer but don't know how they got it. Can you please help me?????
Thanks,
Jill
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
%283a-5%29%5E3
which is
(3a-5)*(3a-5)*(3a-5)
First FOIL (3a-5)(3a-5)
9a^2 - 5a - 5a + 25
9a^2 - 10a + 25
Multiply this by (3a-5), using the old method of multiplying you learned in grade school.
9a^2 - 10a + 25
. . X . . 3a - 5
----------------
you should get
27a^3 - 75a^2 + 125a - 125