13.4
Factoring Trinomials of the Form ax 2
bx
c, a
1 by Grouping
Learning Objectives
1. Use the grouping method to factor trinomials of the form ax2 + bx + c.
2. Key Vocabulary: grouping method, trinomial.
A. Factor using the Grouping Method
Step for factoring a trinomial by grouping
1. Factor out a greatest common factor, if there is one other than 1.
2. For the resulting trinomial ax 2 bx c , a 1 , find two numbers whose product is ac and whose
sum is b.
3. Write the middle term, bx, using the factors found in step 2.
4. Factor by grouping.
Example 1.
Factor completely.
1.
x 15 6 x 2
2.
45x 3
1
45x 2
50 x