Transcript Topic 10
Topic 10 What you know and what you are going to know • You know how to add and subtract whole numbers, like 6 + 9 • Today you are going to learn how to add and subtract fractions with like denominators. • How do you add fractions? • How do you subtract fractions? 3 Objective • Add and subtract fractions and mixed numbers expressing answers in simplest form. 4 When do you think you might need to add or subtract fractions? •Following a recipe Measuring or cutting lengths Think back to some of the things you already know • • • • • • Simplest form Equivalent fractions Common denominators Factors (GCF) and (LCF) Multiples (GCM) and (LCM) How to compare Writing Fractions in Simplest Form • A fraction is in simplest form when the only common factor of the numerator and denominator is 1. 1. 2 • 1 = 2 3•1=3 2. 27 36 1. List the common factors. 2. Find the GCF. 3. Divide by the GCF. 7 Mixed Number / Improper Fraction • When changing a mixed number to an improper fraction, you need to multiply the denominator by the integer, then add the numerator to the product. • Rewrite 4 1/2 as an improper fraction. 9/ 2 8 Adding Fractions 1. Check for common denominators. 2. Once the denominators are the same, add the numerators. 3. Always simplify your answer. 4. If your answer doesn’t match an answer choice, try to simplify the answer choices. 9 practice Video with like denominators • http://www.youtube.com/watch?v=52ZlXs FJULI Find the Sum 1. 8/9 + 2/9 = • 10/9 = 1 1/9 2. 9/16 + 4/32 = • 22/32 = 11/16 3. 8 2/3 + 6 1/2 = • 14 7/6 = 15 1/6 12 Subtracting Fractions 1. Check for common denominators. 2. Once the denominators are the same, subtract the numerator. 3. Always simplify your answer. 4. If your answer doesn’t match an answer choice, try to simplify the answer choices. 13 Find the Difference 1. 4/5 - 2/5 = • 2/5 2. 8/12 - 4/9 = • 8/36 = 2/9 3. 9 - 6 5/8 = • 2 3/8 14 video with unlike denominators • http://www.graspr.com/videos/Addingand-Subtracting-Fractions-With-UNLIKEDenominators-1 Review! • How do you add fractions? • How do you subtract fractions? 16 Find the Difference, Find the Sum 1. 5 - 2 3/4 •2¼ 2. 4/5 + 3/10 • 1 1/10 17