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Make them into equivalent fractions with the same denominator, then the numerators can be subtracted and the resultant fraction simplified (if possible).
The first choice is the denominator for the equivalent fractions. Ideally this should be the lowest common multiple (LCM) of the given denominators, but just multiplying the two given denominators together will do.
The fractions can then be made into equivalent fractions with this chosen denominator.
If finding the LCM is too difficult, a simple "butterfly" (or "cross multiply") method can be used:
- multiply the numerator of the first fraction by the denominator of the second fraction as the numerator of the equivalent first fraction;
- multiply the denominator of the first fraction by the numerator of the second fraction as the numerator of the equivalent second fraction;
- multiply the denominators together as the denominator of both of the equivalent fractions;
- subtract the new numerators, keeping the new denominator;
- simplify the result if possible.
eg 3/5 - 1/2 = 3x2/5x2 - 5x1/5x2
= 6/10 - 5/10
= 1/10
eg 5/6 - 1/2 = 5x2/6x2 - 6x1/6x2
= 10/12 - 6/12
= 4/12
= 1x4/3x4
= 1/3
The same method is used for addition of fractions with different denominators: add instead of subtract the numerators of the equivalent fractions.
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Why are two fractions converted into like fractions?
Because you can't add or subtract fractions that have different denominators. Making them like fractions, by multiplying so the denominators are the same, you can add and/or subtract them.
How do you add two fractions that have like denominators?
In fractions, you can NEVER add or subtract
What is the definition to unlike denominators?
unlike denominators: the bottom number of a fraction. to have unlike denominators you must have two fractions with a different number on the bottom of each fraction.
How do you find the difference of two fractions with the same denominator?
Subtract as if there were no denominators.
When adding fractions with unlike denominators it is most helpful if the fractions are renamed using the?
If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators. To add fractions with unlike denominators, rename the fractions with a common denominator.
What is the benefit of getting the least common multiple of two or more numbers?
It will enable you to add and subtract fractions with unlike denominators.
Why are two fractions converted into like fractions?
Because you can't add or subtract fractions that have different denominators. Making them like fractions, by multiplying so the denominators are the same, you can add and/or subtract them.
How do you add two fractions that have like denominators?
In fractions, you can NEVER add or subtract
What way is subracting fractions with unlike denominators like adding fractions with unlike denominators?
If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators.
What is an common multiple of the denominators for two or more fractions?
Multiplying the denominators together of two or more unlike fractions will get you a common multiple.
What is the definition to unlike denominators?
unlike denominators: the bottom number of a fraction. to have unlike denominators you must have two fractions with a different number on the bottom of each fraction.
How do you find the difference of two fractions with the same denominator?
Subtract as if there were no denominators.
When adding fractions with unlike denominators it is most helpful if the fractions are renamed using the?
If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators. To add fractions with unlike denominators, rename the fractions with a common denominator.
How can you find common denominator for two unlike fractions?
multiply the two denominators
How is adding like fractions and adding unlike fractions the same?
If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators. To add fractions with unlike denominators, rename the fractions with a common denominator. Then add and simplify.
Adding unlike fractions?
If the denominators are not the same, then you have to use equivalent fractions which do have a common denominator . To do this, you need to find the least common multiple (LCM) of the two denominators. To add fractions with unlike denominators, rename the fractions with a common denominator. Then add and simplify.
How can the greatest common factor and least common multiple help you work with fractions?
Finding the GCF of the numerator and the denominator of a fraction and dividing them both by it will give you the simplest form of that fraction. Finding the LCM of unlike denominators and converting them to it will make it possible to add and subtract unlike fractions.
