Using The AC Method To Factor A Trinomial When a>1

To factor a trinomial when a>1 such as  2x2+ 5 + 11x

First be sure to put it in descending order so that the term of highest degree ax2 is first followed by the term bx and c last. In this case we rewrite

2x2+ 5 + 11x as 2x2+ 11x + 5

 

 

Second find the product of a and c in ax2+bx +c.

In this case a=2 and c=5. The product ac=2(5)=10

 

 

Third in order to factor 2x2+ 11x + 5 we need factors of 10 that sum to the coefficient of the middle term 11. The table below will help us to find the factors.

 

Factors of ac or 10

Sums

2 and 5

2+5=7

1 and 10

1+10=11

The factors we want to use are 1 and 10.

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Created by: Dr.Marcia L. Tharp

On 3/21/01

Send comments to: tctharm@tc.cc.va.us