5.2 adding and subtracting fractions updated
- 1. Before the bell rings... Copy the weekly planner. Have your covered textbook with you. Put these in order for least to greatest. ¾ 2/3 5/8 5/7 Anna saw 171 fish during her 38-minute drive. At this rate, how many did she see in the first two minutes?
- 2. Before the bell rings... Copy the weekly planner. Have your covered textbook with you. Put these in order for least to greatest. ¾ 2/3 5/8 5/7 Anna saw 171 fish during her 38-minute drive. At this rate, how many did she see in the first two minutes? 5/8, 2/3, 5/7, 3/4 9 fish
- 3. Fractions Adding and Subtracting
- 4. Essential Questions What is the value of studying fractions? What is the relationship between good number sense and working with fractions?
- 5. Rule for +, - Must have or get COMMON DENOMINATORS Add or subtract only the numerators, keeping the same denominator. Simplify fraction into lowest terms
- 6. Find the LCM Find the new numerators Add the numerators Simplify the fraction
- 7. Subtract Find the LCM Find the new numerators Subtract the numerators Simplify the fraction
- 8. Try these examples = = = = =
- 10. EXAMPLE 1 Adding and Subtracting Fractions Rewrite fractions using LCD of 40 . Write sum over LCD. Evaluate numerator. Rewrite fractions using LCD of 30 . Write difference over LCD. Evaluate numerator. Simplify. a. 7 8 + – 2 5 = 35 40 – 16 40 + = 35 +( – 16) 40 19 40 = b. 3 10 5 6 – = 9 30 25 30 – = 9 – 25 30 = – 16 30 8 15 – =
- 11. GUIDED PRACTICE for Example 1 Find the sum or difference. Then simplify if possible. Rewrite fractions using LCD of 40 . Write difference over LCD. Evaluate numerator. 2. 3 4 9 10 – = 30 40 36 40 – = 30 – 36 40 – 6 40 = – 3 20 = 3 20
- 12. GUIDED PRACTICE for Example 1 Find the sum or difference. Then simplify if possible. Rewrite fractions using LCD of 108 . Write sum over LCD. Evaluate numerator. 3. 5 12 – 7 9 + = 45 108 – 84 108 + = 45 – 84 108 – 39 108 = 13 36 13 36 = –
- 13. GUIDED PRACTICE for Example 1 Find the sum or difference. Then simplify if possible. Rewrite fractions using LCD of 90 . Write difference over LCD. Evaluate numerator. Simplify. 5. 1 6 11 15 – = 15 90 66 90 – = 15 – 66 90 – 51 90 = – 17 30 =
- 14. Homework Page 240 #1-13, 36-39