Expert: Steve Holleran - 3/17/2008

Question
how would you facor this problem

2x^2+15x+12

also if you have time.....
what is the method to factor cubed roots

Answer
Hi Mike,

This does not factor over the rational numbers.  You would use the quadratic formula to find the roots, and then (x - each root) would be the factors:


 x = [-15 +/-sqrt(225 - 4(24)] / 4

   = [-15 +/- sqrt(129)] / 4

So you would have :

     (x - [-15 + sqrt(129)/4])(x - [-15 - sqt(129)]/4).

On the cube root question, are you asking how to factor

(x^3 + y^3) and (x^3 - y^3)?  If so, then they go:

(x^3 + y^3) = (x + y)(x^2 - xy + y^2)

and

(x^3 - y^3) = (x - y)(x^2 + xy + y^2).

I'm not sure what else you would mean.

Steve