Dividing FractionsDate: 8/4/96 at 16:1:48 From: Jeffrey Paul Goins Subject: Dividing fractions Dear Dr. Math, Why do you flip the second fraction when dividing fractions (who figured that out anyway)? Thank you! Levi Goins Date: 8/5/96 at 11:29:51 From: Doctor Anthony Subject: Re: Dividing fractions Why when dividing fractions do you turn the second one upside down and multiply? Example 5/(1/2) = 5*2 = 10 By keeping the rules consistent this rule is easy to derive. A fraction is unchanged if you multiply top and bottom by the same number. In this case if we multiply top and bottom by 2 (which is 1/2 turned upside down) we get: (5*2)/{(1/2)*2} = 10/1 = 10 You will notice that by multiplying top and bottom by the bottom fraction turned upside down we are ensuring that the denominator of the original fraction becomes equal to 1. In practice this is achieved by applying the rule you quoted. -Doctor Anthony, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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