SOLUTION: I need some help with this problem.... Thanks Factor by grouping 21x^3 - 15x^2 + 56x-40= and this one please... x^3 +4x^2-2x-8= thanks for all your help...I am ju

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: I need some help with this problem.... Thanks Factor by grouping 21x^3 - 15x^2 + 56x-40= and this one please... x^3 +4x^2-2x-8= thanks for all your help...I am ju      Log On


   

Question 482922: I need some help with this problem....
Thanks
Factor by grouping
21x^3 - 15x^2 + 56x-40=
and this one please...
x^3 +4x^2-2x-8=
thanks for all your help...I am just stuck on these few problems...
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Factor by grouping
21x^3 - 15x^2 + 56x-40
----
3x^2(7x-5) + 8(7x-5)
----
= (7x-5)(3x^2+8)
==========================

and this one please...
x^3 +4x^2-2x-8
----
x^2(x+4)-2(x+4)
----
(x+4)(x^2-2)
=================
cheers,
Stan H.
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