# How do you find the LcD of the fractions with the following denominators: 30, 18, and 15?

##### 1 Answer

Dec 18, 2016

#### Explanation:

To find the LCD, I like to first do a prime factorizations:

The LCD will have all the elements that each of the denominators have.

First we have 2's. Both the 30 and the 18 have a 2, so we put in one:

Next to 3's. The 18 has two of them and so we put in two:

Now to 5's. Both the 30 and the 15 have one, so we put in one:

There are no other primes to include, so we can now multiply it out:

So let's try it out - let's say we're doing:

We want the LCD to be 90: