Tham khảo tài liệu 'symbols of addition 3', ngoại ngữ, anh ngữ phổ thông phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | THEA MATH REVIEW Fractions To work well with fractions it is necessary to understand some basic concepts. Simplifying Fractions Rule a bc b To simplify fractions identify the Greatest Common Factor GCF of the numerator and denominator and divide both the numerator and denominator by this number. Example Simplify If. The GCF of 63 and 72 is 9 so divide 63 and 72 each by 9 to simplify the fraction 63 9 7 72 98 63 7 72 8 Adding and Subtracting Fractions Rules To add or subtract fractions with the same denominator a c- bb b To add or subtract fractions with different denominators Ỉ d ad cb bd To add or subtract fractions with like denominators just add or subtract the numerators and keep the denominator. Examples Ấ l_6 5 7 7 7 and 8 8 8 100 THEA MATH REVIEW To add or subtract fractions with unlike denominators first find the Least Common Denominator or LCD. The LCD is the smallest number divisible by each of the denominators. For example for the denominators 8 and 12 24 would be the LCD because 24 is the smallest number that is divisible by both 8 and 12 8 X 3 24 and 12 X 2 24. Using the LCD convert each fraction to its new form by multiplying both the numerator and denominator by the appropriate factor to get the LCD and then follow the directions for adding subtracting fractions with like denominators. Example 1 2 _ 1 5 2 3 3 5 3 5 5 3 5 6 15 15 11 15 Multiplication of Fractions Rule a OXJL b d b X d Multiplying fractions is one of the easiest operations to perform. To multiply fractions simply multiply the numerators and the denominators. Example M Í If any numerator and denominator have common factors these may be simplified before multiplying. Divide the common multiples by a common factor. In the example below 3 and 6 are both divided by 3 before multiplying. Example H 2 101 ----------------------------------- THEA MATH REVIEW ------------------------------------------ Dividing Fractions Rule a a b d b c b X c Dividing fractions is equivalent to multiplying the .
