ax bx c  GENERAL METHOD FOR FACTORING TRINOMIALS OF THE FORM

advertisement

GENERAL METHOD FOR FACTORING TRINOMIALS OF THE FORM

ax 2

 bx c

where

a

1

1. Construct product/sum chart and determine the pair of numbers

(factor pair) which has a product equal to the value of c

and a sum equal to the value of b

.

For example, if factoring x

2 

4 x a product of -12 and a sum of 4.

12

, find the factor pair which yields

PRODUCT = - 12

1

 

12

SUM = 4

1 ( 12)

 

11 Not Good

1 12

2

 

6

1 12 11 Not Good

2 ( 6) 4 Not Good

2 6 2 6 4 WORKS!

2. Insert the factor pair directly into the constant locations in the binomial factors. Since the factor pairs turned out to be -2 and 6, the factored form is  x

2

 x

6

.

Check your answer by multiplying.



GENERAL METHOD FOR FACTORING TRINOMIALS OF THE FORM

ax 2  bx c

where

a

0,1

1. Construct product/sum chart in same manner as for trinomials where a=1 HOWEVER, determine the factor pair which has a product equal to the value of a c

and a sum equal to the value of b

.

For example, given the trinomial

6 x

2 

17 x

14

, you would look for a factor pair which has a product of -84 (from

6

 

14

) and a sum of -

17. In this case, the factor pair turns out to be 4 and -21.

2. Use this factor pair to break the linear (middle) term into two parts:

6 x

2 

17 x

14 becomes

6 x

2 

21 x

4 x

14

3. Group the first two terms and the last two terms and factor out the

GCF from each of the groups:

(6 x

2  x

 x

14)

3 (2 x

  x

7)

4. Complete by factoring out the GCF between groups. In this case, the GCF is the binomial (2x-7).

2 x

  x

2

.

5. Check your answer by completing the multiplication.

Download