Dividing Fractions

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Dividing Fractions
What is a reciprocal? How do you test a
reciprocal?
A reciprocal is the inverse of a fraction. If you
multiply a fraction by its reciprocal they should
equal 1.
Ex ¾ 4/3
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Dividing Fractions
Brainpop
Dividing Fractions KEEP CHANGE FLIP
What is a reciprocal? How do you test a
reciprocal?
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Why Dividing FractionsRequires Inverting The
Divisor                                         
                                                  
                     Let's use our simple example
to actually validate this strange Rule for
division. If you really think about it, we are
dividing a fraction by a fraction, which forms
what is called a "complex fraction". It actually
looks like this...                             
                                                  
        
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• When working with complex fractions, what we want
  to do first is get rid of the denominator (1/3),
  so we can work this problem easier.
• You may recall that any number multiplied by its
  reciprocal is equal to 1. And since, 1/3 x 3/1
  1, we can use the reciprocal property of 1/3
  (3/1) to make the value of the denominator equal
  to 1.

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• But, you might also remember that whatever we do
  to the denominator, we must also do to the
  numerator, so as not to change the overall
  "value".
• So let's multiply both the numerator and
  denominator by 3/1...

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Which gives us...                              
                                                  
              
Here's what happened... By multiplying the
numerator and denominator by 3/1, we were then
able to use the reciprocal property to eliminate
the denominator. Actually, without our helpful
Rule, we would have to use all of the steps
above. So, the Rule for dividing fractions
really saves us a lot of steps! Now that's the
simplest explanation I could come up with for WHY
and HOW we end up with a Rule that says we must
invert the divisor!
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