Review of how to find the LCD (least common denominator):

First consider ordinary fractions such as:

To find the LCD, begin by factoring the denominators completely:

=
=

The LCD is then the product that contains each factor the LARGEST number of times that it appears in any ONE of these denominators.

Here, the largest number of 2's is 3, the largest number of 3's is 1, and the largest number of 5's is also 1.

LCD ==

Next, let's try rational expressions such as:

Factor the denominators:

=
=

Thus, the LCD ==

Finally, let's try another one with rational expressions:

=
=

Since each factor is used once as the largest number of times, we get:

LCD =