C S4­2 Greatest Common Factor.notebook
October 10, 2016
Section 4.2 ­ Greatest Common Factor
I can find the greatest common factor of 2 or more numbers
Today's Lesson: * Section 4.2 Greatest Common Factor * Sorry I don't have the take home tests graded yet
Instructions: * Take out Assign #17 (Pink Outline) If done today $1 (I'll collect)
* Grade Assign #16 (Sect 4.1) out of 15 example 13/15 Assign #16 Answers 3 minutes 2) composite
4) 1, 5, 25
6) 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
8) composite, 88=2x44
10) composite, 39=3x13
12) prime, only 1x61=61
14) prime, only 1x41=41
16) composite 201=3x67
18) 72 20) 22x17
2
2
22) 2x13
24) 3 x5 26) 22x32x17
28) C
34) 17, 19, 23, 29, 31
Review Factors. example: 18, 12, 30
factors of 18: 1, 2, 3, 6, 9, 18
factors of 12: 1, 2, 3, 4, 6, 12
factors of 30: 1, 2, 3, 5, 6, 10, 15, 30
Define "Common Factor": A whole number that is a factor of two or more nonzero whole numbers:
Common Factors
factors of 18: 1, 2, 3, 6, 9, 18
factors of 12: 1, 2, 3, 4, 6, 12
factors of 30: 1, 2, 3, 5, 6, 10, 15, 30
Define "Greatest Common Factor": The largest common factor
Greatest Common Factor
factors of 18: 1, 2, 3, 6, 9, 18
factors of 12: 1, 2, 3, 4, 6, 12
factors of 30: 1, 2, 3, 5, 6, 10, 15, 30
Sep 7­5:46 AM
I can find the greatest common factor of 2 or more numbers
Sep 7­5:46 AM
I can find the greatest common factor of 2 or more numbers
Lets Practice (Homework examples)
METHOD #1) Greatest Common Factor of the numbers (by listing)
(ex) 8, 20, 66
factors of 8:
factors of 20:
factors of 66:
More Homework examples
METHOD #2) Greatest Common Factor (by prime factorization/
factor tree)
(ex) Tell whether the set of numbers are relatively prime. 48, 120
(ex) 3, 14, 23
factors of 3:
factors of 14:
factors of 23:
2 24 2 60
Relatively prime: when the greatest common factor (GCF) two or more numbers is one, the numbers are called relatively prime.
2 3
(ex) Tell whether the set of numbers are relatively prime. 9, 28, 35
factors of 9:
factors of 28:
factors of 35:
GCF = what every they both have in common, then you multiply them together.
48
120
2 12 6 10
2 6 2 3 2 5
48 = 2 x 2 x 2 x 2 x 3
so the GCF of 48 and 120 = ??????
Sep 7­5:46 AM
I can find the greatest common factor of 2 or more numbers
Now You Try Use the method you prefer (list) or (factor tree)
Find the GCF and tell whether the set of numbers are relatively prime. (ex) 39, 65
(ex) 24, 35
(ex) 60, 96
120 = 2 x 2 x 3 x 2 x 5 Sep 7­5:46 AM
homework: due upon request (see syllabus) Assign Date Due
# assigned date
Description
New Chapter 4
#16 10/7 10/10 Sect 4.1, pg 167, #1­29, 34, 35
#17 10/7 10/10
Ch 4 (Pink) Outline
#18 10/10 10/11 Sect 4.2, pg 172, #1­16 use the method you like best!
Any Questions?
Sep 7­5:46 AM
Sep 7­5:46 AM
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