SOLUTION: Factor sum of two cubes. y^3 + 125

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Factor sum of two cubes. y^3 + 125      Log On


   

Question 763822: Factor sum of two cubes.
y^3 + 125
Found 2 solutions by ramkikk66, tommyt3rd:
Answer by ramkikk66(644) About Me  (Show Source):
You can put this solution on YOUR website!

We will use the identity: %28a%5E3+%2B+b%5E3%29+=+%28a+%2B+b%29%2A%28a%5E2+-+a%2Ab+%2B+b%5E2%29

%28x%5E3+%2B+125%29+=+%28x%5E3+%2B+5%5E3%29+=+%28x+%2B+5%29%2A%28x%5E2+-+5%2Ax+%2B+5%5E2%29

Factored solution is:

%28x%5E3+%2B+125%29+=+%28x+%2B+5%29%2A%28x%5E2+-+5%2Ax+%2B+25%29

:)

Answer by tommyt3rd(5050) About Me  (Show Source):
You can put this solution on YOUR website!
use the identity:


%0D%0Ax%5E3%2By%5E3+=+%28x%2By%29%28x%5E2-xy%2By%5E2%29%0D%0A

with x=5 to get

%0D%0Ay%5E3%2B5%5E3+=+%28y%2B5%29%28y%5E2-5y%2B25%29%0D%0A