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Example Questions
Example Question #1 : Least Common Denominator
Find the least common denominator of the following fractions:
The denominators are 7, 3, and 9. We have to find the common multiple of 7, 3, and 9.
Multiples of 7: 7, 14, 21, 28, 35, 42, 49, 56, 63, 70
Multiples of 3: 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63
Multiples of 9: 9, 18, 27, 36, 45, 54, 63, 72, 81, 90
The least common multiple of the 3 denominators is 63.
Example Question #1 : Least Common Denominator
What is the least common denominator of the following fractions?
Solution 1
The least common denominator is the least common multiple of the denominators.
We list the multiples of each denominator and we find the lowest common multiple.
Multiples of 19: 19, 38, 57, 76, 95, 114, 133, 152, 171, 190
Multiples of 5: 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100
The lowest common multiple in both lists is 95.
Solution 2
19 and 5 are prime numbers. They have no positive divisors other than 1 and themselves.
The least common denominator of two prime numbers is their product.
Example Question #1 : Least Common Denominator
Find the least common denominator of and .
To find the least common denominator for these two fractions, multiply the denominators together.
Example Question #1 : Least Common Denominator
Find the least common denominator for and
To find the least common denominator for these two fractions, multiply the denominators together.
Example Question #8 : Least Common Denominator
Find the least common denominator between and .
Start by factoring the numerator and denominator for each fraction.
So when the two simplified fractions are compared, they actually have the same denominator, which will be the least common denominator.
Example Question #9 : Least Common Denominator
Find the least common denominator of and
Start by simplifying both fractions.
Now, to find the least common denominator, multiply the denominators together.
Example Question #2 : Least Common Denominator
Find the least common denominator of and
To find the least common denominator, multply the two denominators together.
Example Question #21 : Understanding Rational Expressions
Find the least common denominator between and
To find the least common denominator, multply the two denominators together.
Example Question #22 : Understanding Rational Expressions
Find the least common denominator between and
To find the least common denominator, multply the two denominators together.
Example Question #13 : Least Common Denominator
Find the least common denominator for and .
Start by simplifying both fractions.
Now, to find the least common denominator for the two simplified fractions, multiply the denominators together.
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