How can using the GCF and LMC help you you add subtract and multiply fractions?

Answer 1

In order to add or subtract fractions, the denominator (bottom number) has to be the same. In order to make it the same, you find the LCM and multiply the fraction by whatever is necessary to make the denominator the LCM. FOR EXAMPLE:

1/3 + 2/5

The LCM of 3 and 5 is 15.

To make the 3 in 1/3 15, you multiply the whole fraction by 5 over 5 (it simplifies to 1 so you aren't really changing the fraction by multiplying it by 1).

1/3 * 5/5 is 5/15

You multiply 2/5 times 3 over 3 using the same principle

2/5 * 3/3 is 6/15

NOW you can add 5/15 and 6/15 to get 11/15.

Answer 2

To add and subtract unlike fractions, find the LCM of the denominators and convert them to equivalent like fractions. You don't have to do anything to fractions to multiply them, but you may need to reduce one after multiplying. To do that, find the GCF of the numerator and the denominator and divide both of them by it. If the GCF is 1, the fraction is in its simplest form.

Answer 3

Knowing the LCM of the denominators will help you to find a least common denominator of unlike fractions, which will allow you to add and subtract them successfully. Knowing the GCF and LCM will not help you in multiplying them, but knowing the GCF of the numerator and denominator of a fraction will help you reduce it if necessary.

Answer 4

When adding and subtracting unlike fractions, it is necessary to find the LCM of the denominators, called the least common denominator. Once you have found the LCD, you can convert the fractions to equivalent fractions with a common denominator and proceed with the adding and/or subtracting. Finding an LCM will have no effect on multiplying fractions.

Answer 5

To add and subtract fractions, you need common denominators. To find the common denominator, take the LCM of the denominators you wish to add or subtract.