Find the LCM of 8, 15, and 20?

Answer 1

Math 81 Answers to Quiz 3 (Sec.4433)
(1) (2 points) Prime factorize the composite number 4200, show work.
4200 = 23 £ 3 £ 52 £ 7
(2) (2 points) Find the LCM of 8, 15, and 20, show work.
8 = 23, 15 = 3 £ 5, 20 = 22 £ 5
=) LCM = 23 £ 3 £ 5 = 120
Note: The LCM is the product of all the different prime fractors, each of which is
raised to the highest power.
(3) (2 points) Find the GCF of 32, 40, and 56, show work.
32 = 25 £ 3, 40 = 23 £ 5, 56 = 23 £ 7
=) GCF = 23 = 8
Note: The GCF is the product of all the common prime fractors, each of which is
raised to the lowest power.
(4) (3 points) Is each of the following statements True or False?
(a) 5
5 is equal to 1. True.
(b) For whatever number a, the fraction a
a is equal to 1. False.
Note: When a is a nonzero number, then it is True.
(c) 5
0 is equal to 0. False.
Note: It is undefined. (5
0 is not a number.)
(5) (2 points) Converting to an improper fraction:
(a) 347
= 25
7 (b) 1635
= 83
5
(6) (2 points) Converting to a mixed number:
(a) 71
9 =789
(b) 53
12 =4 5
12
(7) (2 points) Find the missing numerator:
(a) 7
13 = 35
65 (b) 9= 54
6

Answer 2

The LCM of 8, 15, and 20 is 120.

Answer 3

120:
factors of 8: 2^3
factors of 15: 3, 5
factors of 20: 5, 2^2

all the 2-based powers in one column:
2^2
2^3

all the 3-based powers in another column:
3

all the 5-based powers in another column:
5
5

Now pick the biggest power out of all the columns:
2^3
3
5 (if the powers are the same value, you only pick one of them)

Multiply them all together = 120

Answer 4

8=2*2*2
15=3*5
20=5*2*2
You need a number that contains every factor in each number:
2*2*2*3*5= 120