Concept 5/6: Adding and Subtracting Fractions

Adding and Subtracting Fractions

And the importance of a common denominator

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Now can you add the following:


 $\frac{9}{5}+\frac{3}{2}\ =?$  


Hint: Use the fractions you calculated in the last 2 questions!

TIME TO ADD!

Take out (or make room in your notebook for) "CW 5-Adding Fractions" and complete it as we go!!

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 $\frac{5}{4\ }+\ \frac{3}{4}$  =

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 $\frac{11}{8\ }+\frac{7}{8}=$  

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 $\frac{1}{2}+\frac{3}{2}$  

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 $\frac{8}{5\ }+\frac{9}{5}$  

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 $\frac{7}{6}+\frac{7}{6}=$  

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 $\frac{4}{5}+\frac{7}{5}=$  

TIME TO SUBTACT!

Now take out or make some room for "CW 6 - Subtracting Fractions"

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 $\frac{13}{8}-\frac{13}{8}=$  

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 $\frac{9}{8}-\frac{5}{8}=$  

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 $\frac{13}{7}-\frac{5}{7}=$  

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 $\frac{10}{7}-\frac{6}{7}=$  

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 $\frac{3}{2}-\frac{1}{2}=$  

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 $\frac{10}{7}-\frac{1}{7}=$  

LET'S GO BACK TO CW 5!

Different denominators now!!

Multiple Choice

How would you convert 1/2 to a fraction with a denominator of 8?

• Multiply both numerator and denominator by 4

• Add 4 to both the numerator and denominator

• Multiply both numerator and denominator by 8

• I thought about it, but I'm not sure...

Multiple Choice

Now let's look at number 9.  Write 9/5 with a denominator of 10.

• $\frac{9}{10}$

• $\frac{18}{10}$

• $\frac{10}{5}$

• I'm not sure how to do that

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Now write 3/2 with a denominator of 10

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Now write 3/2 with a denominator of 10

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 $\frac{9}{5}+\frac{3}{2}=$  

Hint: use your answers from the last 2 problems!

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 $\frac{3}{2}+\frac{5}{7}=$  

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 $1+\ \frac{13}{8}=$  

NOW LET'S SUBTRACT!

Go back to CW 6...

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 $\frac{6}{5}-\frac{2}{7}=$  

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 $2-\frac{7}{8}=$  

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 $\frac{3}{2}-\frac{4}{3}=$  

What you need to do now:

1. Finish CW 5 and 6
2. Scan them (or take a picture) and submit them on Canvas in the correct Module.
3. Make sure you took the quiz for last week!