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How do you add or subtract fractions with uncommon denominators?
Wiki User
∙ 13y ago
In order to add and subtract using non-common denominators, you must find a common denominator. The easiest way of finding one is to multiply the two denominators. But there may be a smaller number (least common denominator).
Mutiply the numerator and denominator of the first number by the second denominator (effectively multiplying by 1). Then multiply the numerator and denominator of the second number by the original denominator of the first number. This will leave the denominators the same.
Example : add 1/3 and 1/4
Multiply 1/3 by 4/4 to yield 4/12. Multiply 1/4 by 3/3 to yield 3/12. Add the numerators.
1/3 + 1/4 = 4/12 + 3/12 = 7/12
Wiki User
∙ 13y ago
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When you add or subtract fractions with unlike denominators why do you have to find LCM?
Because to add fractions, the denominators must be equal.
How would you add or subtract fractions with like denominators?
The same way you would add or subtract whole numbers, leaving the denominators alone.
When do you need a common denominator?
The denominators must be the same before you can add or subtract fractions.
Can you explain adding and subtracting fractions with like denominators?
When you add or subtract fractions with like denominators, you just add or subtract the numerators and put them over the same denominator. For example, 3/5 - 2/5 = (3 - 2)/5 = 1/5
When you add or subtract fractions with the same denominators what happens to the denominator in your answer?
It stays the same. Only the numerators change.
How do you add and subtract by fractions?
If the fractions have the same denominator, add and subtract the numerators as if the denominators weren't there and put the result over that denominator. Reduce if possible. If the fractions have different denominators, find the LCM of the denominators and convert the fractions to equivalent fractions with like denominators. Then add and subtract the numerators as if the denominators weren't there and put the result over that denominator. Reduce if possible.
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
When you add or subtract fractions with unlike denominators why do you have to find LCM?
Because to add fractions, the denominators must be equal.
How would you add or subtract fractions with like denominators?
The same way you would add or subtract whole numbers, leaving the denominators alone.
What do you not have to think about when you add or subtract fractions?
Whether the denominators are common or not.
How is finding the LCM revelant when adding and subtracting fractions?
To add and subtract fractions, you need common denominators. To find the common denominator, find the LCM of the denominators you wish to add or subtract.
Do you always have to have like numerators in fractions before you can add or subtract?
No, the denominators have to be the same.
Why does the equivalent fraction make adding and subtracting fractions easier?
You cannot add or subtract fractions with different denominators. If the denominators are different then you need to work with equivalent fractions.
Why would you want to rename fractions with the LCD?
Possible reasons: To add or subtract fractions, To compare fractions with different denominators.
When do you need a common denominator?
The denominators must be the same before you can add or subtract fractions.
How to add and subtract mixed numbers?
Convert them to improper fractions with common denominators and proceed.
