Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
3 8 Adding and Subtracting Fractions By Shelly Jamison Review: Adding Fractions with common denominators 3 4 7 8 8 8 Adding Fractions with different denominators Problem: You can’t add fractions with different denominators without getting them ready first. They will be ready to add when they have common denominators. Solution: Turn fractions into equivalent fractions with a common denominator. finding the LCM. You can do this by Finding the Lowest Common Denominator • The lowest common multiple of two numbers is the lowest number in BOTH lists of multiples 1 1 2 3 Multiples of 2 are 2, 4, 6, 8, 10…… Multiples of 3 are 3, 6, 9, 12, ……… What is the lowest common multiple? Finding the Lowest Common Denominator • The lowest common multiple of two numbers is the lowest number they will BOTH divide into 1 1 2 3 2 divides into 2, 4, 6, 8….. 3 divides into 3, 6, 9…. What is the lowest number 2 and 3 both divide into? 1 1 2 3 You can’t add fractions with different denominators + The Lowest Common Multiple of 2 and 3 is 6 so turn all fractions into sixths 1 3 1 2 3 2 5 2 3 3 2 6 6 6 Special form of 1 1 2 2 5 Lowest common denominator is 10 so make all fractions tenths 5 4 9 10 10 10 ? ? 3 3 2 7 2 9 14 23 1 3 7 3 7 21 21 21 21 21 21 It is 3/3 It is 7/7 So I multiply So I multiply 3/7 by 3/3 2/3 by 7/7 Finally the fractions are READY to add. I just have to add the numerators 9+14=23 What is special the lowest What What special form formnumber 3 and 77divide ofBOTH 1 of will1 change will change 3 into? to 21. to 21. Hmmmm? Hmmmm? It is 21. So that is my Hmmmmm?????? common denominator Now 3x3=9 and 2x7=14 Now I know the new numerators Adding Mixed Numbers • • • • • Separate the fraction and the whole number sections. Find a common denominator. Add the fractions. Add the whole numbers. Simplify!!!! 22 11 22 55 11 33 7 5 6 7 5 6 Subtract Mixed Numbers • Separate the fraction and the whole number sections. • Find a common denominator. • Subtract the fractions. • Note: You may have to regroup by taking a whole number and adding the denominator amount to the numerator (pieces). • Subtract the whole numbers. • Simplify!!!! 2 3 4 -3 12 4 2 9 4 -3 12 12 14 9 3 -3 12 12 5 12