SOLUTION: Reduce the rational expression to lowest terms: a^3+27b^3/ a^2-9b^2 I tried separating the equations out like this: (a+3b)(a+3b)(a+3b)/ -1(a+3b)(a+3b) I end up with: a^2

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Reduce the rational expression to lowest terms: a^3+27b^3/ a^2-9b^2 I tried separating the equations out like this: (a+3b)(a+3b)(a+3b)/ -1(a+3b)(a+3b) I end up with: a^2      Log On


   

Question 882992: Reduce the rational expression to lowest terms:
a^3+27b^3/
a^2-9b^2
I tried separating the equations out like this:
(a+3b)(a+3b)(a+3b)/
-1(a+3b)(a+3b)
I end up with:
a^2+9b^2/
a-3b
When I type in the answer into my online homework, it says it is incorrect.
Thank you.
Found 2 solutions by josgarithmetic, ankor@dixie-net.com:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
Your sum of cubes formula used was wrong.

a%5E3%2B27b%5E3=a%5E3%2B%283b%29%5E3
%28a%2B3b%29%28a%5E2-a%2A3b%2B%283b%29%5E2%29, you could try to derive the rule or look for the rule listed in your Algebra book, or in some algebra book.

...still need more help?...

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
%28a%5E3%2B27b%5E3%29%2F%28a%5E2-9b%5E2%29
The numerator, you have to use the "special Factoring formula" as the "Sum of cubes"
namely: (a^3 + b^3) = (a+b)(a^2- ab + b^2), in your problem this would be
:
%28%28a%2B3b%29%28a%5E2-+3ab+%2B+9b%5E2%29%29%2F%28%28a-3b%29%28a%2B3b%29%29; factored the denominator as difference if squares
Cancel (a+3b)
%28%28a%5E2-+3ab+%2B+9b%5E2%29%29%2F%28%28a-3b%29%29; about all you can do with it