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Equivalent Fractions. Lesson 4-7. Bell Work. Name the greatest common factor for each pair. 1. 5 and 10 2. 9 and 12 3. 20 and 24 4. 10 and 14 5. 6 and 8 6. 8 and 15. 5. 3. 4. 2. 2. 1. Today’s Math Standards. Number Sense 1.0 (this is what we are working toward)
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Equivalent Fractions Lesson 4-7
Bell Work Name the greatest common factor for each pair. 1.5 and 10 2. 9 and 12 3. 20 and 24 4. 10 and 14 5. 6 and 8 6. 8 and 15 5 3 4 2 2 1
Today’s Math Standards • Number Sense 1.0 (this is what we are working toward) • Students compare and order positive and negative fractions, decimals, and mixed numbers. Students solve problems involving fractions, ratios, proportions, and percentages: • Number Sense 2.4 • Determine the least common multiple and the greatest common divisor of whole numbers; use them to solve problems with fractions (e.g., to find a common denominator to add two fractions or to find the reduced form for a fraction).
Equivalent Fractions • We use the GCF and the LCM to make equivalent fractions • GCF to make smaller equivalent fractions • Reduce • Simplify • Put in lowest terms • LCM to make equivalent fractions • Make common denominators • Addition • Subtraction • Comparing (with and without number lines)
Key Vocabulary • equivalent fractions • Fractions that name the same number • improper fraction • A fraction whose numerator is larger than the denominator • mixed number • A whole number and a fraction
6 10 3 5 x 2 columns 2 columns = 15 25 3 5 x 5 columns 5 columns x = x Notice how all three of the rectangles still have these same 5 rows. The only thing that has changed is the number of columns. Equivalent Fractions Different fractions can name the same number. 3 5 6 10 15 25 = =
3 5 6 10 15 25 In the diagram = . These are called equivalent fractions because they are different expressions for the same nonzero number. = To create fractions equivalent to a given fraction, multiply or divide the numerator and denominator by the same nonzero number.
Remember! A fraction with the same numerator and denominator, such as is equal to 1. 2 2 Find two fractions equivalent to . 1 5 2 10 14 Multiply the numerator and denominator by 2. = 7 2 1 Multiply the numerator and denominator by 3. 5 3 15 21 = 7 3
15 21 5 7 10 14 The fractions , , and are equivalent, but only is in simplest form. A fraction is in simplest form when the greatest common divisor of its numerator and denominator is 1. 5 7
6 12 Find two fractions equivalent to . 1 6 2 12 24 Multiply the numerator and denominator by 2. = 12 2 1 6 ÷ 2 12 ÷ 2 Divide the numerator and denominator by 2. 3 6 =
18 ÷6 24 ÷ 6 18 ÷6 24 ÷ 6 18 ÷6 24 ÷ 6 18 ÷6 24 ÷ 6 18 24 Write the fraction in simplest form. Find the GCD of 18 and 24. 18 = 2 • 3 • 3 The GCD is 6 = 2 • 3. 24 = 2 • 2 • 2 • 3 1 18 24 3 4 Divide the numerator and denominator by 6. = =
15 ÷15 45 ÷ 15 15 45 Write the fraction in simplest form. Find the GCD of 15 and 45. 15 = 3 • 5 The GCD is 15 = 3 • 5. 45 = 3 • 3 • 5 1 1 3 15 45 Divide the numerator and denominator by 15. = =
To determine if two fractions are equivalent, simplify the fractions.
4 6 28 42 2 3 and are equivalent because both are equal to . Determine whether the fractions in each pair are equivalent. 4 6 28 42 and Simplify both fractions and compare. 1 4 6 4 ÷ 2 6 ÷ 2 2 3 = = 1 2 3 28 42 28 ÷ 14 42 ÷ 14 = =
3 5 4 5 = 20 25 are not equivalent because their simplest and 6 10 forms are not equal. Determine whether the fractions in each pair are equivalent. 6 10 20 25 and Simplify both fractions and compare. 1 6 ÷ 2 10 ÷ 2 6 10 3 5 = = 1 4 5 20 ÷ 5 25 ÷ 5 20 25 = =
3 9 6 18 and 1 3 1 3 = 6 18 3 9 6 18 1 3 and are equivalent because both are equal to . Determine whether the fractions in each pair are equivalent. Simplify both fractions and compare. 1 3 9 3 ÷ 3 9 ÷ 3 1 3 = = 1 6 ÷ 6 18 ÷ 6 1 3 = =
1 3 3 16 = 9 48 are not equivalent because their simplest and 4 12 forms are not equal. Determine whether the fractions in each pair are equivalent. 4 12 9 48 and Simplify both fractions and compare. 1 4 ÷ 4 12 ÷ 4 1 3 4 12 = = 1 9 ÷3 48 ÷ 3 9 48 3 16 = =
3 5 8 5 is an improper 1 is a mixed fraction. Its numerator is greater than its denominator. number. It contains both a whole number and a fraction. 3 5 8 5 = 1
Converting Between Improper Fractions and Mixed Numbers as a mixed number. A. Write 13 5 First divide the numerator by the denominator. Use the quotient and remainder to write the mixed number. 3 5 13 5 = 2 2 3 B. Write 7 as an improper fraction. First multiply the denominator and whole number, and then add the numerator. + Use the result to write the improper fraction. 3 7 + 2 2 3 23 3 = = 7 3
1 2 = 2 15 6 as a mixed number. A. Write First divide the numerator by the denominator. Use the quotient and remainder to write the mixed number. 3 6 15 6 = 2 1 3 B. Write 8 as an improper fraction. First multiply the denominator and whole number, and then add the numerator. + Use the result to write the improper fraction. 3 8 + 1 1 3 25 3 = 8 = 3
To add or subtract fractions with different denominators, you must rewrite the fractions with a common denominator. In this case, the fractions need to be made equivalent.
Helpful Hint The LCM of two denominators is the least common denominator (LCD) of the fractions.
24 30 2 2 5 2 3 Find the Lowest Common Denominator for and . 24 = 2 x 2 x 2 x 3 30 = 2 x 3 x 5 LCM = 2 x 2 x 2 x 3 x 5 = 120 x 4 x 4 x 5 x 5
Lesson Quiz 1 2 1 2 3 6 3 6 , , 512 410 1 8 1 8 2 2 20 48 20 48 9 48 9 48 & & 1. Write two fractions equivalent to . 2. Determine if and are equivalent. 3. Write the fraction in simplest form. 4. Write as a mixed number. 5. Write 4 as an improper fraction. 6. Find the LCD, and write equivalent fractions for and . 1. Write two fractions equivalent to . 2. Determine if and are equivalent. 3. Write the fraction in simplest form. 4. Write as a mixed number. 5. Write 4 as an improper fraction. 6. Find the LCD, and write equivalent fractions for and . 12 24 no no 1 3 1 3 16 48 16 48 17 8 31 7 31 7 3 7 5 12 5 12 3 16 LCD = 48
Guided Practice • Holt – Online video tutorial and practice • Holt Online Practice • Holt-common denominators