Adding and Subtraction Common Denominators

How do you find the common denominator when adding fractions with unlike denominators?

• By multiplying the denominators together

• By finding the greatest common factor

• By finding the least common multiple

• By adding the denominators together

In the case that the given fractions are dissimilar, how shall we make them similar being the only way to proceed to addition or subtraction of fractions?

• Add the denominators together. Whatever is the sum, that will be the denominator for both fractions.

• Just choose either of the denominator from both fractions that you wanted as new denominator before you proceed to adding and subtracting the numerators.

• Simply find LCD and use such LCD as the new denominator for both fractions. Then find equivalent fractions for each given.

• All of the above.

Add and simplify 4/7 and 3/7.

• 6/7

• 1

• 1 4/7

• 7/49

Add and simplify if needed. 3/4 + 1/8 =

• 7/8

• 4/8

• 7/32

• 4/32

When can we add or subtract fractions?

• We can add or subtract fractions if and only if their denominators are the same.

• We can only add or subtract fractions if and only if their numerators are the same.

• We can add or subtract fractions if and only if they are dissimilar.

• We can add or subtract fractions simply by adding or subtracting their numerators as well as adding or subtracting their denominators.

7/8 - 7/12

• 7/24

• 1/4

• 7/12

• 4/24

What is the last step in adding or subtracting fractions?

• Find their LCD

• Add or subtract the whole number

• Copy the denominator

• Simplify

What is the least common denominator of 1/2 and 3/7?

• 2

• 14

• 7

• 28

3/7 + 2/7

• 5/14

• 6/49

• 5/7

• 1/7

Q1. What is the result of 14/16?

• A) 14/16

• B) 7/8

• C) 8/7

• D) 4/10