Question

Part A: Find the LCM of 7 and 8. Show your work. (3 points)

Part B: Find the GCF of 54 and 81. Show your work. (3 points)

Part C: Using the GCF you found in Part B, rewrite 54 + 81 as an expression of two factors. One factor is the GCF and the other is the sum of two numbers that do not have a common factor. Show and explain your work.

Answer 1

Part A: 56

Work:

7: 7, 14, 21, 28, 35, 42, 49, 56

8: 8, 16, 24, 32, 40, 48, 56, 64

Part B: 27

Work:

54: 54, 27, 9, 3, 1

81: 81, 27, 9, 3, 1

Part C: 27(2+3)

Work:

27×2 = 54

27×3 = 81

(27×2)+(27×3) = 54+81

(27×2)+(27×3)=27(2+3)

Explaining work:

First you find the numbers that multiply the GCF by to get the product (for 54 it is 2 and for 81 it is 3). Then you replace the the products with the equations (27×2) for 54 and (27×3) for 81 to get (27×2)+(27×3). Then simplify to get 27(2+3).

Answer 2

Part A:

LCM of 7 and 8 is 56.

7*8 = 56

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Part B:

GCF of 54 and 81 is 27.

54: 1, 2, 3, 6, 9, 18, 27, 54.

81: 1, 3, 9, 27, 81.

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Part C:

GCF of 54 and 81 is 27.

54 / 27 = 2

81 / 27 = 3

Final expression: 27(2 + 3)