Adding and Subtracting Rational Numbers

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Multiple Choice

Can a rational number have 0 as a denominator?

• No

• Yes

Adding/Subtracting Rational Numbers

• Must have a common denominator!

• Once you have a common denominator, you add/subtract the numerator.

Reviewing parts of a fraction

• Numerator = the top number

• Denominator = the bottom number

Multiple Select

What is the top number of a fraction called?

• Denominator

• Numerator

Multiple Select

What is the bottom number of a fraction called?

• Denominator

• Numerator

Adding fractions with a common denominator

• Add the numerators

• Keep the denominators the same

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Multiple Choice

$$\frac{1}{6}+\frac{3}{6}=$$  

• $$\frac{2}{6}$$  

• $$\frac{4}{6}$$  

• $$\frac{4}{12}$$  

Multiple Choice

$$\frac{4}{9}+\frac{4}{9}=$$  

• $$\frac{8}{9}$$  

• $$\frac{4}{9}$$  

• $$\frac{8}{18}$$  

Adding fractions with different denominators

• Multiply the denominators (to get a common denominator - QCD)

• Multiply the numerator of the first fraction by the opposite denominator

• Multiply the numerator of the second fraction by the opposite denominator

Multiple Choice

$$\frac{2}{3}+\frac{1}{6}=$$  

• $$\frac{3}{6}$$  

• $$\frac{3}{9}$$  

• $$\frac{15}{18}$$  

Multiple Choice

$$\frac{1}{9}+\frac{5}{2}=$$  

• $$\frac{47}{18}$$  

• $$\frac{6}{18}$$  

• $$\frac{6}{11}$$  

Multiple Choice

$$\frac{4}{3}+\frac{1}{8}=$$  

• $$\frac{35}{24}$$  

• $$\frac{5}{11}$$  

• $$\frac{5}{24}$$  

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Find the LCM of 21 and 7
21: 21, 42, 63
7: 7, 14, 21, 28
The LCM is 21. Therefore both fractions with have the same denominator which is 21.

• denominators must be equal

• if not, convert using LCM

• when done, simplify using GCF​

​

Demoninators must be the same in order to begin!

Adding and subtracting fractions

Fill in the Blank

$$\frac{7}{9}+\frac{1}{6}$$  

Try this!

Fill in the Blank

$$\frac{4}{5}-\frac{3}{4}$$  

Try this!

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