SOLUTION: i need to factor 8x^9 + 729y^3 and I seem to mess it up everytime I try to do this. Could you give me steps in which to take to solve this probem?

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: i need to factor 8x^9 + 729y^3 and I seem to mess it up everytime I try to do this. Could you give me steps in which to take to solve this probem?      Log On


   

Question 259515: i need to factor 8x^9 + 729y^3 and I seem to mess it up everytime I try to do this. Could you give me steps in which to take to solve this probem?
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Factor:
8x%5E9%2B729y%5E3 First, do you recognise this as the sum of two cubes?
%282x%5E3%29%5E3%2B%289y%29%5E3
Recall that the sum of two cubes is factorable as:
A%5E3%2BB%5E3+=+%28A%2BB%29%28A%5E2-AB%2BB%5E2%29 and, here: A+=+2x%5E3 and B+=+9y, so...
8x%5E9%2B729y%5E3+=+highlight%28%282x%5E3%2B9y%29%284x%5E6-18x%5E3y%2B81y%5E2%29%29