Greatest Common Factor

Agenda Tuesday, Dec. 1

homework   10    p. 193  #1 ­ 20, 25 ­ 28

Do NowWrite using exponents

1.   Evaluate:  4x2 + 3 for x = ­5 4(­5)2 + 3

4 * 25 + 3

100 + 3 = 103

Correct homework

4­3 Prime Factorization & Greatest Common Factor

A Prime number can only be divided evenly by itself AND one.

One is not a prime because it can ONLY be divided evenly by one.

Are these number Prime or Composite?

Prime factorization - a composite number written as the product of it's prime factors

Divide by prime numbers beginning with 2.

182933

Gather the primes and put in exponential form.

2*3*32*32

How Do You Findthe Greatest Common Factor

(GCF) Using Prime Factorization?

Prime Factors of 20Prime Factors of 12

Greatest Common Factor (GCF)

1) Which numbers are in both circles? 2, 2

2) Find the product of the numbers that are in both circles. 4

Prime Factors of 20Prime Factors of 12

20 = 2 x 2 x 512 = 2 x 2 x 3

3

2

2

5

The Greatest Common Factor (GCF) is the product of the common prime factors. The GCF of 12 and 20 is 4.

Move the rectangle to check your answer.

Prime Factors of 28Prime Factors of 16

28 = 2 x 2 x 716 = 2 x 2 x 2 x 2

Directions: Find the prime factorization of each number. Use the Venn diagram below to show the prime factors of 16 and 28. Then use it to find the GCF.

Prime Factors of 56Prime Factors of 42

56 = 2 x 2 x 2 x 742 = 2 x 3 x 7

Directions: Find the prime factorization of each number. Use the diagram below to show the prime factors of 42 and 56. Then use it to find the GCF.

Directions: Use Venn diagrams to find the GCF of each set of numbers.

1) 20, 30 GCF = 10

2) 16, 40 GCF = 8

3) 21, 45 GCF = 3

4) 27, 45 GCF = 9

Move the rectangles to check your answers.

Directions: Use Venn diagrams to find the GCF of each set of numbers.

1) 20, 30 GCF = 10

2) 16, 40 GCF = 8

3) 21, 45 GCF = 3

4) 27, 45 GCF = 9

Move the rectangles to check your answers.

Directions: Use Venn diagrams to find the GCF of each set of numbers.

1) 20, 30 GCF = 10

2) 16, 40 GCF = 8

3) 21, 45 GCF = 3

4) 27, 45 GCF = 9

Move the rectangles to check your answers.

Directions: Use Venn diagrams to find the GCF of each set of numbers.

1) 20, 30 GCF = 10

2) 16, 40 GCF = 8

3) 21, 45 GCF = 3

4) 27, 45 GCF = 9

Move the rectangles to check your answers.

Attachments