Section 4-4

Factoring ax2 + bx + c = 0a is not 1

Swing & Divide

Objectives

•I can factor trinomials using Swing and Divide Method

Factoring a Trinomial

• When factoring an expression with 3 terms you will always get two factors

• x2 + bx + c

( #)( *)x x

Swing and Divide Method

• The Swing & Divide method is very similar to Reverse FOIL, but with 2 extra steps:

• You can use this method when the number in front of the x2 term is not 1

• EX: 2x2 – x - 3

Swing & Divide

• 2 Steps:

• Swing and

• Divide

• Don’t do one without doing the 2nd

Swing & Divide Method

22 6x x

Swing

2 12x x Now use FOIL

( 4)( 3)x x

4 3( )( )

2 2x x Divide by Swing #

Final Factors

( 2)(2 3)x x

Reducing and Checking

• Always reduce fractions before finding final factors

• Use TWO Finger Check when done

Example 2

23 7 6x x

Swing

2 7 18x x Now use FOIL

( 9)( 2)x x

9 2( )( )

3 3x x Divide by Swing #

Final Factors

( 3)(3 2)x x

Example 3

28 2 3x x

Swing

2 2 24x x Now use FOIL

( 6)( 4)x x

6 4( )( )

8 8x x Divide by Swing #

Final Factors

(4 3)(2 1)x x

3 1( )( )

4 2x x Reduce

Board 122 5 3x x

2 5 6x x ( 6)( 1)x x

6 1( )( )

2 2x x

( 3)(2 1)x x

Board 222 3 9x x

2 3 18x x ( 6)( 3)x x

6 3( )( )

2 2x x

( 3)(2 3)x x

Board 329 12 4x x

2 12 36x x ( 6)( 6)x x

6 6( )( )

9 9x x

(3 2)(3 2)x x

Homework

• WS 5-4