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Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion


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April 27th, 2018, 08:15 AM   #1
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Factoring large odd/uneven numbers?

I fell into this problem when trying to figure out a way to subtract fractions with big uneven denominators, and am stuck. How do we use prime factorization for numbers like this?

2/57 - 9/67

Is it okay if you get fractions in prime factorization? What should I do? Thank you!
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April 27th, 2018, 08:32 AM   #2
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a/u - b/v = (av - bu) / (uv)
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April 28th, 2018, 11:47 AM   #3
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As Denis implies, you may have been taught to find the least common denominator when adding or subtracting fractions, but that is not at all necessary. What is necessary is to find a common denominator. And that is most simply done by finding the product of the denominators.

EDIT: In the case of your example, where denominators are both prime numbers and cannot be factored, their product is the least common denominator, but such a product will always be a common denominator.

Last edited by JeffM1; April 28th, 2018 at 12:07 PM.
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