SOLUTION: How do I factor by grouping? 7x^3-28x^2-3x+12 I started by (7x^3-28x^2)+(-3x+12) after I did this 7x(x^2-4x)+-3(x+-4) Answer (7x-3)(x-4) This is not right I don't think I

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: How do I factor by grouping? 7x^3-28x^2-3x+12 I started by (7x^3-28x^2)+(-3x+12) after I did this 7x(x^2-4x)+-3(x+-4) Answer (7x-3)(x-4) This is not right I don't think I       Log On


   

Question 132288: How do I factor by grouping?
7x^3-28x^2-3x+12
I started by
(7x^3-28x^2)+(-3x+12)
after I did this
7x(x^2-4x)+-3(x+-4)
Answer
(7x-3)(x-4)
This is not right I don't think I need help! I am not getting it.
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

7x%5E3-28x%5E2-3x%2B12 Start with the given expression

%287x%5E3-28x%5E2%29%2B%28-3x%2B12%29 Group like terms


7x%5E2%28x-4%29-3%28x-4%29 Factor out the GCF 7x%5E2 out of the first group. Factor out the GCF -3 out of the second group


%287x%5E2-3%29%28x-4%29 Since we have the common term x-4, we can combine like terms

So 7x%5E3-28x%5E2-3x%2B12 factors to %287x%5E2-3%29%28x-4%29