Algebra II : Understanding Rational Expressions

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #1 : Least Common Denominator

Find the least common denominator of the following fractions:

Possible Answers:

Correct answer:

Explanation:

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 #5 : Least Common Denominator

What is the least common denominator of the following fractions?

Possible Answers:

Correct answer:

Explanation:

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 #6 : Least Common Denominator

Find the least common denominator of  and .

Possible Answers:

Correct answer:

Explanation:

To find the least common denominator for these two fractions, multiply the denominators together.

Example Question #7 : Least Common Denominator

Find the least common denominator for  and 

Possible Answers:

Correct answer:

Explanation:

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 .

Possible Answers:

Correct answer:

Explanation:

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 

 

Possible Answers:

Correct answer:

Explanation:

Start by simplifying both fractions.

Now, to find the least common denominator, multiply the denominators together.

Example Question #1 : Least Common Denominator

Find the least common denominator of  and 

Possible Answers:

Correct answer:

Explanation:

To find the least common denominator, multply the two denominators together.

Example Question #11 : Least Common Denominator

Find the least common denominator between  and 

Possible Answers:

Correct answer:

Explanation:

To find the least common denominator, multply the two denominators together.

Example Question #12 : Least Common Denominator

Find the least common denominator between  and 

Possible Answers:

Correct answer:

Explanation:

To find the least common denominator, multply the two denominators together.

Example Question #13 : Least Common Denominator

Find the least common denominator for  and  .

Possible Answers:

Correct answer:

Explanation:

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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