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Okay okay, so you can compare fractions, but can you add, subtract, multiply, and divide them?

Okay okay, so you can compare fractions, but can you add, subtract, multiply, and divide them?. Notes for August 19. Adding/Subtracting Fractions. When you add/subtract fractions, you only add or subtract the numerator of the fraction You do NOTHING to the denominator !!!.

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Okay okay, so you can compare fractions, but can you add, subtract, multiply, and divide them?

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  1. Okay okay, so you can compare fractions, but can you add, subtract, multiply, and divide them? Notes for August 19

  2. Adding/Subtracting Fractions • When you add/subtract fractions, you only add or subtract the numerator of the fraction • You do NOTHING to the denominator!!!

  3. Adding/Subtracting Fractions

  4. Adding/Subtracting Fractions with Unlike Denominators • If the denominators do not match, you can NOT just add/subtract the fractions • Just like when you compare fractions, to add/subtract fractions, you must find a least common denominator

  5. So Let’s Review from Yesterday: How Do I Find the LCD? What is the least common multiple of 3 and 7?

  6. So Let’s Review from Yesterday: How Do I Find the LCD? • The least common denominator of 3 and 7 is 21. • Remember the golden rule of fractions: • When you find the least common denominator, you MUST also multiply the numerator by the same value

  7. So Let’s Review from Yesterday: How Do I Find the LCD?

  8. Adding/Subtracting Fractions with Unlike Denominators • Find the sum of

  9. Adding/Subtracting Fractions with Unlike Denominators • First, you must find the least common denominator of 7 and 11 • The least common denominator of 7 and 11 is 77

  10. Adding/Subtracting Fractions with Unlike Denominators • Next, you need to convert the fractions into equivalent fractions with the least common denominator

  11. Adding/Subtracting Fractions with Unlike Denominators • Now, you can add the numerators

  12. Adding/Subtracting Fractions with Unlike Denominators • Reduce if necessary • It is not necessary in this case

  13. Adding/Subtracting Fractions with Unlike Denominators • Now it’s your turn! 1.) 2.)

  14. Multiplying Fractions • Unlike when you add/subtract fractions, when you multiply fractions, you multiply both the numerators and the denominators • When you multiply fractions, you multiply directly across the rows.

  15. Multiplying Fractions • Find the product of

  16. Multiplying Fractions • First multiply across the rows 8 15

  17. Multiplying Fractions • Reduce if necessary • It is not necessary in this case

  18. Multiplying Fractions • Now it’s your turn! 1.) 2.)

  19. Multiplying Fractions with Mixed Numbers • A mixed number includes both a whole number and a fraction • Example –

  20. Multiplying Fractions with Mixed Numbers • You cannot multiply fractions when they are in mixed number form. You must make the fractions improper to multiply. • A improper fraction is a fraction where the numerator is greater than the denominator.

  21. Converting Mixed Numbers to Improper Fractions – Squeeze in Texas

  22. Converting Mixed Numbers to Improper Fractions – Squeeze in Texas • To convert a mixed number to an improper fraction, squeeze in Texas – tx + x

  23. Converting Mixed Numbers to Improper Fractions – Squeeze in Texas • tx tells us what to do when we convert the mixed number to an improper fraction • First, we multiply the whole number and the denominator + x

  24. Converting Mixed Numbers to Improper Fractions – Squeeze in Texas • Next, add the product to the numerator + x

  25. Converting Mixed Numbers to Improper Fractions – Squeeze in Texas • Finally, place the sum over the old denominator and you have your new improper fraction + x

  26. Multiplying Fractions with Mixed Numbers • Find the product:

  27. Multiplying Fractions with Mixed Numbers • First, convert the two numbers into improper fractions by squeezing in Texas + x

  28. Multiplying Fractions with Mixed Numbers • First, convert the two numbers into improper fractions by squeezing in Texas + x

  29. Multiplying Fractions with Mixed Numbers • Multiply as normal – straight across

  30. Alright let’s recap … • What do you do when you add fractions? • What if they have unlike denominators?

  31. Alright let’s recap … • What do you do when you subtract fractions? • What if they have unlike denominators?

  32. Alright let’s recap … • What do you do when you multiply fractions? • Is there a shortcut?

  33. Alright let’s recap … • Okay so we’ve added, we’ve subtracted, and we’ve multiplied … • So now what? It’s time for … DIVISION!!!!

  34. So how do we divide? • I have three special words to help you divide fractions …

  35. Dividing Fractions • COPY • DOT • FLIP

  36. Dividing Fractions • When you divide fractions, what you need to do is … 1.) Copy the first fraction 2.) Put a dot for multiplication 3.) Flip the second fraction 4.) Multiply as normal 5.) Reduce if necessary

  37. Dividing Fractions

  38. Dividing Fractions:Step 1 – Copy the first fraction

  39. Dividing Fractions:Step 2 – Dot (for multiplication)

  40. Dividing Fractions:Step 3 – Flip the second fraction

  41. Dividing Fractions:Step 4 – Multiply as normal

  42. Dividing Fractions:Step 5 – Reduce if necessary Do I have to be reduced? I am improper. No, fractions can be improper for Ms. Siems.

  43. Dividing fractions • Now it’s your turn! 1.) 2.)

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