posted by bebe on .
in what way is subtracting fractions with unlike denominators like adding fractions with unlike denominators?
Like fractions are fractions with the same denominator. You can add and subtract like fractions easily - simply add or subtract the numerators and write the sum over the common denominator.
Before you can add or subtract fractions with different denominators, you must first find equivalent fractions with the same denominator, like this:
Find the smallest multiple (LCM) of both numbers.
Rewrite the fractions as equivalent fractions with the LCM as the denominator.
When working with fractions, the LCM is called the least common denominator (LCD)
Subtracting Fractions Is Actually Easier Than Adding Fractions
When subtracting fractions with different denominators, we follow the same process we used for adding different fractions. But since everybody doesn't start with addition, we provide the same level of detail for subtraction.
First of all, when subtracting fractions with different denominators, the first step in the Rule says that we must change these fractions so that they have the "same denominator".
Here are the steps for subtracting fractions with different denominators. We will break-down each step just like before to make sure you've got it. Then we will subtract some tougher numbers. And finally, we will help you pull everything together. Okay!
So, here are the steps.
Build each fraction so that both denominators are equal. Remember, when subtracting fractions, the denominators must be equal. So we must complete this step first. What this really means is that you must find what is called a Common Denominator. Most of the time you will be required to work the problem using what's called the Least Common Denominator (LCD). In either case you will build each fraction into an equivalent fraction.
Re-write each equivalent fraction using this new denominator
Now you can subtract the numerators, and keep the denominator of the equivalent fractions.
Re-write your answer as a simplified or reduced fraction, if needed.
hope this helps
5/8's as a product of a whole number anda unit fraction