Question

Find the LCD that would eliminate the fractions in this equation. 3a/7+2/3=7/9

Answer 1

All you have to do is find the lowest possible number that contains all denominators as potential factors. For example, the LCD of the (1/3) + (1/2) is 6, because the lowest number that has factors of 3 and 2 is 6, since 3 x 2 = 6.

Keep in mind though that it's not necessarily just multiplying all denominators together. Say you have (1/2) + (1/4) + (1/7). If you multiply all denominators together, you get 2 x 4 x 7 = 56. While 56 is a common denominator, it is not the LEAST common denominator. The trick is to realize that the denominator 2 is a factor of 4, and because of it, any number that has a factor of 4 also has a factor of 2. In this case, all you'd have to do is multiply 7 and 4 to get 28, which is the the LCD.

With this knowledge, hopefully you can better answer your question.