and Subtracting Fractions PreAlgebra Objectives Add proper fractions Subtract proper fractions Solve a word problem involving addition and subtraction of fractions ID: 415055
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Slide1
Adding and Subtracting Fractions
Pre-Algebra
ObjectivesAdd proper fractionsSubtract proper fractionsSolve a word problem involving addition and subtraction of fractions.
Slide2
Let’s Review:
Converting between Mixed Numbers and Improper Fractions
Slide3
C
Equivalent Fractions
Do the C!
How can you change a
mixed number to an improper fraction
?
Keep the original denominator
Numerator
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d
Equivalent Fractions
Kick over the fraction
How can you change an improper fraction to a mixed number?
Whole Number
Keep the original denominator
Numerator
When changing from an improper fraction to a mixed number AND when dividing a fraction to get a decimal,
Remember: BO TI
Bottom, Outside
Top, Inside
BO TISlide5
BO TI
The bottom of the fraction goes on the outside
The top of the fraction goes on the insideBO TI
Slide6
Methods for Adding and Subtracting Fractions:
The Butterfly
Cross Multiply & Smile
Slide7
Make a Butterfly
8
=
3
=
=12
Slide8
Cross Multiply & Smile
XD
XD
Slide9
Add the fractions. Simplify.
1.
Use Polling Tools
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Add the fractions. Simplify.
2.
Use Polling Tools
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Subtract the fractions.
3.
Use Polling Tools
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Subtract the fractions. Simplify.
4.
Use Polling Tools
Slide13
Methods for Adding and Subtracting Fractions:
Find the Least Common Denominator
Slide14
What is the least common multiple
of 8 and 5?
8: 8, 16, 24, 32, 40…
5: 5, 10, 15, 20, 25, 30, 35, 40…What is the least common multiple
of 2 and 4?
2: 2, 4… 4: 4… Find the L.C.M.Notice: Sometimes the L.C.M. is one of the original numbers.
Slide15
Example A
Add Fractions with Unlike Denominators
A.
Find the least
common multiple. Get a common denominator. Add the fractions.Simplify.
Slide16
Example B
Subtract Fractions with Unlike Denominators
B.
Follow Integer Rules for Adding:
Same Signs: Add #’s, Common Sign
Different Signs: Subtract #’s, Greater #’s Sign
Slide17
Kim completed
of a video game. Then, Joel completed an additional
of the game. What fraction of the game did Kim and Joel complete together?
Example C
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Methods for Adding and Subtracting Fractions:
Use a TableSlide19
First Fraction Goes Here:
Numerator
Denominator
Second Fraction Goes Here:NumeratorDenominator
Complete the miniature multiplication table
1527
2
10
35
7
Adding Fractions
Add the diagonal.
Take common denominator.Slide20
Adding Fractions
Add the fractions. Simplify if possible.Slide21
Adding Fractions
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First Fraction Goes Here:
Numerator
Denominator
Second Fraction Goes Here:Numerator
Denominator
Complete the miniature multiplication table561
4
5
6
24
20
Reduce your answer if possible.
Subtracting Fractions
Subtract the diagonal.
Take common denominator.
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Subtracting Fractions
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Subtracting Fractions
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Topics
: Adding and Subtracting Fractions with Unlike Denominators
Video/LinkMath Playground Videohttp://www.mathplayground.com/howto_fractions_diffden.htmlKhan AcademyVideohttps://www.khanacademy.org/math/arithmetic/fractions/Adding_and_subtracting_fractions/v/adding-fractions-with-unlike-denominators
Math Playground: Practice adding fractions with unlike denominatorshttp://www.mathplayground.com/fractions_add.htmlScholastic Study Jam: Interactive Practice Step by Stephttp://studyjams.scholastic.com/studyjams/jams/math/fractions/add-sub-unlike-denom.htm
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