Find the LCM 21c^3b^8,7c^2b^3,15c^5b^7

Question

Need to find the LCM of  21c^3b^8,7c^2b^3,15c^5b^7

Answer 1

first, the numbers

the lcm of 21, 7, and 15

21 = 3 * 7

7 = 7

15 = 3 * 5

for an lcm you times together a set of numbers that includes enough numbers to make each of those factors (???) like this:

to make 21 you need a 3 and a 7

to make 7 you just need 7

to make 15 you need a 3 and a 5

to make the lcm, you want 3 * 5 * 7 because 3 * 5 * 7 has a 3 * 7 (to make 21), a 7 (to make 7), and a 3 * 5 (to make 15).

the lcm of 21, 7, and 15 is 3 * 5 * 7 = 105

now the c's

the lcm of c^3, c^2, and c^5 is c^5

now the b's

the lcm of b^8, b^3, and b^7 is b^8

the lcm of the whole thing is 105(c^5)(b^8)