why do you multiply fractions instead of dividing? cause my teacher always said to invert and multiply and i was confused why.

Guest Jun 13, 2017

#1**+2 **

It is easier to multiply fractions.

For example:

\(\frac34\div\frac57=\frac34\,*\,\frac75\)

Then, just multiply straight across.

\(=\frac{3*7}{4*5}=\frac{21}{20}\)

It ** is ** true that

\(\frac34\div\frac57=\frac{3\div5}{4\div7}=\frac{21}{20}\)

But how are you going to evaluate 3 / 5 and 4 / 7 without using a calculator or long division?

And...to see why inverting and multiplying is the same as dividing, take a simple example:

\(10\div2=10\,*\,\frac12=\frac{10}{1}\,*\,\frac12=\frac{10}{2}\)

hectictar
Jun 14, 2017

#1**+2 **

Best Answer

It is easier to multiply fractions.

For example:

\(\frac34\div\frac57=\frac34\,*\,\frac75\)

Then, just multiply straight across.

\(=\frac{3*7}{4*5}=\frac{21}{20}\)

It ** is ** true that

\(\frac34\div\frac57=\frac{3\div5}{4\div7}=\frac{21}{20}\)

But how are you going to evaluate 3 / 5 and 4 / 7 without using a calculator or long division?

And...to see why inverting and multiplying is the same as dividing, take a simple example:

\(10\div2=10\,*\,\frac12=\frac{10}{1}\,*\,\frac12=\frac{10}{2}\)

hectictar
Jun 14, 2017