Find the least common denominator of each set of fractions. − 2 9 , 7 15 -\frac29,\frac{7}{15}

This problem asks us to find the least common denominator of the fractions. And what I can see is that I have the fractions -2/9 and 7/15. Now, the least common denominator is going to be the least common multiple of 9 and 15, the denominators of my fraction. And to find this least common denominator, we've learned a couple strategies we can use. We can list out multiples of each of the numbers, or what we can do is use prime factorization. For this case, I'm going to use prime factorization to solve this problem. So let me list my denominators 9 and 15. Now what I'm going to do is break these down into prime numbers. 9 is the same thing as 3 x 3. And 15 is the same thing as 3 x 5. Now, what I need to do is find all the unique prime factors. For 9, I can see we have 3 x 3. And then for 15, I can see we have 13, but we already have 2 3s up here. So, since we have the higher number of 3s up here and we just have 13 for 15, we don't have to worry about that 3 because that's not a unique prime factor. However, this 5 is a unique prime factor since there's only 15 I'm seeing here. So, to find the LCD we just need to find the product of all of these unique prime factors, 3 x 3 x 5. And doing this math here, it all comes out to 45. So, 45 is the least common denominator giving us the solution to our problem.

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4. Fractions

Finding The Least Common Denominator

Prealgebra & Beginning Algebra

4. Fractions

Finding The Least Common Denominator

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Multiple Choice

Find the least common denominator of each set of fractions.
$- \frac{2}{9}, \frac{7}{15}$

$90$

$15$

$135$

$45$

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Find the least common denominator of each set of fractions.
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