1. Warm Up
1. Which of the following is an example of the Associative Property? A = B = 9 C. 9( ) = 9(10) + (11) D. (9 + 10) + 11 = 9 + ( ) 2. What is the slope of the line containing the points with the coordinates (4, -2) and (8, 3)? D
Slope Formula

2. Lesson On: Factoring out the GCF(Greatest Common Factor)
January 6, 2014

3. Finding the GCF GCF- Stands for the Greatest Common Factor.
The Greatest Common Factor, the GCF, is the biggest number that will divide into (is a factor of) both terms.

4. Example
What is the GCF of 4 and 6?
GCF: 2

5. (Hint: Check to see if the smaller number goes into the bigger number)
Let’s try some more
What is the GCF of 12 and 24?
GCF: 12
(Hint: Check to see if the smaller number goes into the bigger number)

6. Can we do the same thing with variables?

7. Let’s try some more with the variables

8. Can you do this one?

9. Let’s put it all together!!!

10. One more like that one!!!
GCF: 4b

11. Remember if you can not do this quickly it is ok write out all of the
factors so that you can work your
way up to being very quick
with finding the GCF!!!

12. Now let’s Factor out the GCF!!!!!

13. Review: What is the GCF of 25a2 and 15a?
Let’s go one step further…
1) FACTOR 25a2 + 15a.
Find the GCF and divide each term
25a2 + 15a = 5a( ___ + ___ )
Check your answer by distributing. 5a 3

14. 2) Factor 18x2 - 12x3. Find the GCF 6x2 Divide each term by the GCF
18x2 - 12x3 = 6x2( ___ - ___ )
Check your answer by distributing. 3 2x

15. 3) Factor 28a2b + 56abc2. GCF = 28ab Divide each term by the GCF
28a2b + 56abc2 = 28ab ( ___ + ___ )
Check your answer by distributing.
28ab(a + 2c2) a
2c2

16. Factor 20x2 - 24xy
x(20 – 24y)
2x(10x – 12y)
4(5x2 – 6xy)
4x(5x – 6y)

17. 5) Factor 28a2 + 21b - 35b2c2 GCF = 7 Divide each term by the GCF
Check your answer by distributing.
7(4a2 + 3b – 5b2c2)
4a2 3b
5b2c2

18. Factor 16xy2 - 24y2z + 40y2 2y2(8x – 12z + 20) 4y2(4x – 6z + 10)
8xy2z(2 – 3 + 5)

19. Independent Practice Time!!!