Objectives Add proper fractions Subtract proper fractions Solve
Objectives • • • Add proper fractions Subtract proper fractions Solve a word problem involving addition and subtraction of fractions. Adding and Subtracting Fractions Pre-Algebra
Let’s Review: Converting between Mixed Numbers and Improper Fractions
Equivalent Fractions How can you change a mixed number to an improper fraction ? C Do the C! Keep the original denominator Numerator
Equivalent Fractions When changing from anan improper How can you change improper to a mixed fraction to a mixed number? number AND when dividing a fraction to get a decimal, Whole Number Kick over the fraction d Remember: BO TI Bottom, Outside Numerator Top, Inside Keep the original denominator
BO TI The bottom of the fraction goes on the outside The top of the fraction goes on the inside BO TI
Methods for Adding and Subtracting Fractions: • The Butterfly • Cross Multiply & Smile
Make a Butterfly 3= =8 =12
Cross Multiply & Smile XD XD
Use Polling Tools Add the fractions. Simplify. 1.
Use Polling Tools Add the fractions. Simplify. 2.
Use Polling Tools Subtract the fractions. 3.
Use Polling Tools Subtract the fractions. Simplify. 4.
Methods for Adding and Subtracting Fractions: • Find the Least Common Denominator
Find the L. C. M. 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… Notice: Sometimes the L. C. M. is one of the original numbers.
Example A Add Fractions with Unlike Denominators A. 1. Find the least common multiple. 2. Get a common denominator. 3. Add the fractions. 4. Simplify.
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
Example C
Methods for Adding and Subtracting Fractions: Use a Table
Adding Fractions Second Fraction Goes Here: 2 7 Numerator Denominator 1 2 7 Numerator First Fraction Goes Here: 5 10 35 Denominator Complete the miniature multiplication table Ad dia d the gon al. Tak den e com m om ina on tor.
Adding Fractions Add the fractions. Simplify if possible.
Adding Fractions
Subtracting Fractions Second Fraction Goes Here: 1 4 Numerator Denominator 5 5 20 Numerator First Fraction Goes Here: 6 6 24 Denominator Complete the miniature multiplication table Reduce your answer if possible. Su btr dia act t gon he al. Tak den e com m om ina on tor.
Subtracting Fractions
Subtracting Fractions
Helpful Links Topics: Adding and Subtracting Fractions with Unlike Denominators Math Playground Video Khan Academy Video Math Playground: Practice adding fractions with unlike denominators Scholastic Study Jam: Interactive Practice Step by Step Video/Link http: //www. mathplayground. com/howt o_fractions_diffden. html https: //www. khanacademy. org/math/a rithmetic/fractions/Adding_and_subtra cting_fractions/v/adding-fractions-with -unlike-denominators http: //www. mathplayground. com/fracti ons_add. html http: //studyjams. scholastic. com/studyj ams/jams/math/fractions/add-subunlike-denom. htm
- Slides: 25