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How do you subtract fractions with unlike denominators?

How do you subtract fractions with unlike denominators?. For example, what is - ?. -. In this lesson you will learn how to subtract fractions with unlike denominators by using fraction bars. We know that fractions need to have the same denominator to subtract them. .

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How do you subtract fractions with unlike denominators?

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  1. How do you subtract fractions with unlike denominators? For example, what is - ? -

  2. In this lesson you will learn how to subtract fractions with unlike denominators by using fraction bars.

  3. We know that fractions need to have the same denominator to subtract them. I can use equivalent fractions to make common denominators. I remember my teacher called this a common denominator.

  4. How do I decide which equivalent fraction to use? This could go on forever! We know that equivalent fractions show equal amounts. = = = = =

  5. When one denominator is a divisor of the other, only one fraction has to be changed. - = 2 is a divisor of 8 so I will make an equivalent fraction for . -

  6. When both denominators are multiples of 10, only one fraction has to be changed. = - I know that is equivalent to

  7. Students begin to subtract without forming a common denominator. ≠ - ≠ -

  8. What is -? - How do I decide which equivalent fractions to form? One denominator is not a divisor of the other. I can multiply any number by 1 without changing its value. Neither denominator is a multiple of 10.

  9. - Look at the denominator of the other fraction. = Multiply the pieces by 3 x Divide each part of the whole by 3 + =

  10. - Look at the denominator of the other fraction. = Multiply the pieces by 2 x Divide each part of the whole by 2 =- + =

  11. - Now I can subtract. = =- =

  12. Sammy says that - = , but Trevan says it subtracts to leave . It’s . It’s

  13. What is - ? - How do I decide which equivalent fractions to form? One denominator is not a multiple of the other. I can multiply any number by 1 without changing its value. Neither denominator is a multiple of 10.

  14. - Look at the denominator of the other fraction. = Multiply the pieces by 3 x Divide each part of the whole by 3 - =

  15. Look at the denominator of the other fraction. = Multiply the pieces by 5 x Divide each part of the whole by 5 =- - - =

  16. Now I can subtract. = - = -

  17. Trevan was correct because - = It’s . Now I see it!

  18. In this lesson you have learned how to subtract fractions with unlike denominators by using fraction bars.

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