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Do Now Find the LCM for each set of numbers. 1. 8 and 12 2. 12 and 18 3. 10 and 12 4. 12 and 24 24 36 60 Course 2 3-8 Adding and Subtracting Fractions.

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Presentation on theme: "Do Now Find the LCM for each set of numbers. 1. 8 and 12 2. 12 and 18 3. 10 and 12 4. 12 and 24 24 36 60 Course 2 3-8 Adding and Subtracting Fractions."— Presentation transcript:

1 Do Now Find the LCM for each set of numbers and and and and Course Adding and Subtracting Fractions 24 Hwk: p 31

2 EQ: How do I add and subtract fractions? Course Adding and Subtracting Fractions M7N1.c Add, subtract, multiply, and divide positive and negative rational numbers; M7N1.d Solve problems using rational numbers

3 From January 1 to March 14 of any given year, Earth completes approximately of its orbit around the Sun, while Venus completes approximately its orbit The illustration shows what the positions of the planets would be on March 14 if they started at the same place on January 1 and their orbits were circular. To find out how much more of its orbit Venus completes than Earth, you need to subtract fractions. Course Adding and Subtracting Fractions

4 Add. Write the answer in simplest form = Add the numerators and keep the denominator. = 6868 = 3434 Simplify. Course Adding and Subtracting Fractions

5 Subtract. Write the answer in simplest form – – 4 11 = 9 – 4 11 Subtract the numerators and keep the denominator. The answer is in the simplest form. = 5 11 Course Adding and Subtracting Fractions

6 Add. Write the answer in simplest form. Check It Out: Example 1A = Add the numerators and keep the denominator. = 6666 = 1 Simplify. Course Adding and Subtracting Fractions

7 Subtract. Write the answer in simplest form – – 4 10 = 7 – 4 10 Subtract the numerators and keep the denominator. The answer is in the simplest form. = 3 10 Course Adding and Subtracting Fractions

8 To add or subtract fractions with different denominators, you must rewrite the fractions with a common denominator. The LCM of two denominators is the lowest common denominator (LCD) of the fractions. Helpful Hint Two Ways to Find a Common Denominator Find the LCM (least common multiple) of the denominators. Multiply the denominators. Course Adding and Subtracting Fractions

9 Add. Write the answer in simplest form = 5 · 4 6 · 4 7 · 3 8 · 3 = = = Course Adding and Subtracting Fractions ==

10 Subtract. Write the answer in simplest form – – 3434 = 2 · 4 3 · 4 3 · 3 4 · 3 Subtract. = – 1 12 Course Adding and Subtracting Fractions = = =

11 Add. Write the answer in simplest form. – = Add = – 2 · 3 7 · · 7 3 · 7 – =+ – Course Adding and Subtracting Fractions

12 Add. Write the answer in simplest form = = = Divide. Course Adding and Subtracting Fractions

13 Subtract. Write the answer in simplest form – 1212 Subtract. = 4 10 – 5 10 = 1 10 – Course Adding and Subtracting Fractions

14 Add. Write the answer in simplest form. – = Add. =+ – – Course Adding and Subtracting Fractions

15 Subtract – = 1 12 = 6 12 – 1 12 = 5 12 In one Earth year, Jupiter completes about of its orbit around the Sun, while Mars completes about of its orbit. How much more of its orbit does Mars complete than Jupiter? Mars completes more of its orbit than Jupiter does Course Adding and Subtracting Fractions

16 Subtract – = 5 12 = 6 12 – 5 12 = 1 12 It takes Michelle hour to drive to work. It takes Luke hour to drive to work. How much longer does it take Luke to drive to work? It takes Luke hour longer to drive to work Course Adding and Subtracting Fractions

17 You Try Add or subtract. Write each answer in simplest form. Insert Lesson Title Here – – You need a nail to go through a -inch door and extend an extra inch. How long should the nail be? in Course Adding and Subtracting Fractions


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