Answers:
LCD needed to combine the variables: 15
LCD needed to combine the constants: 21
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Step-by-step explanation:
If two numbers m and n do not have any common factors (other than 1), then the LCM is m*n. We simply multiply the values.
So for example, the LCM of 2 and 3 is 2*3 = 6.
For the variable terms, the denominators are 5 and 3. So the LCM is 5*3 = 15, and this is the LCD of those variable fractions.
Similarly, the LCD of the constant terms is 21 because 7*3 = 21.
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Again, for all of these examples, the two values had no factors other than 1 in common. If you were dealing with something like the LCM of 8 and 12, then the LCM would not be 8*12 = 96. But we can fix things by dividing that by 4 to get 96/4 = 24 which is the true LCM here.
So the more generalized formula would be (m*n)/(GCF of m and n)
This formula works for the previous section because the GCF was 1.