Question 154620: I am helping my daughter and trying to find the rule on determining the least common denominator. This is from worksheets in Algebra I but doesn't involve a book yet. I am trying to foind the LCD with two different fractions.
Thanks.
Mark
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Example:
Let's say you have 1/24 + 1/75 and want the lcd.
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Find the prime-factor form of each denominator:
24 = 2^3*3
75 = 3*5^2
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The lcd must contain each of the prime numbers to the highest power present
in the denominators.
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So the lcd must have 2,3,and 5 to the highest power present in the
denominators.
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the lcd is (2^3)* (3) * (5^2) = 8*3*25 =
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So, does that work?
The problem was 1/24 + 1/75
Rewrite each fraction with the lcd as its denominator:
Divide 24 into 600 to get 25.
Multiply numerator and denominator of the 1st fraction by 25 to get:
25/600
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Divide 75 into 600 to get 8
Multiply numerator and denominator of the 2nd fraction by 8 to get:
8/600
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Add the two resulting fractions to get:
1/24 + 1/75 = 25/600 + 8/600 = 33/600 = 11/200
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Cheers,
Stan H.
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