SOLUTION: it asked to factor by grouping and i dont understand how to do it 8x^3+6x^2-12x-9

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: it asked to factor by grouping and i dont understand how to do it 8x^3+6x^2-12x-9      Log On


   

Question 82839: it asked to factor by grouping and i dont understand how to do it
8x^3+6x^2-12x-9
Answer by tutorcecilia(2152) About Me  (Show Source):
You can put this solution on YOUR website!
8x%5E3%2B6x%5E2-12x-9%29
%288x%5E3%2B6x%5E2%29%2B+%28-12x%2B9%29
%282x%5E2%29%288x%5E3%2F2x%5E2%2B6x%5E2%2F2x%5E2%29%2B+%28-3%29%28-12x%2F-3%2B9%2F-3%29 [factor out the least common multiply amongst each factor and divide each term by it]
.
%282x%5E2%29%284x%2B3%29%2B+%28-3%29%284x-3%29 [this re-grouping doesn't work becasue each group has a different factor]
.
.
Try to re-arrange the terms, re-group and factor again:
8x%5E3%2B6x%5E2-12x-9%29
%288x%5E3-12x%29%2B%286x%5E2-9%29
%284x%29%288x%5E3%2F4x-12x%2F4x%29%2B%28%283%296x%5E2%2F3-9%2F3%29%29
%284x%29%282x-3%29%2B%28%283%292x-3%29%29
%284x%2B3%29%282x-3%29%29 [re-factor again; this factoring works because the groups now have a common factor (2x-3)]