# Radical fraction

Printable View

• Jul 25th 2011, 11:33 AM
drewm
Radical fraction
how would I write 4/√7 with a fraction whose denominator is even?

Thanks
• Jul 25th 2011, 11:40 AM
Plato
Re: Radical fraction
Quote:

Originally Posted by drewm
how would I write 4/√7 with a fraction whose denominator is even?

$\frac{8\sqrt 7}{14}$
• Jul 25th 2011, 11:57 AM
drewm
Re: Radical fraction
ok thanks, but can you tell me how you got that?
• Jul 25th 2011, 12:01 PM
Plato
Re: Radical fraction
Quote:

Originally Posted by drewm
ok thanks, but can you tell me how you got that?

I multiplied numerator and denominator by $2\sqrt 7~.$
• Jul 25th 2011, 12:04 PM
e^(i*pi)
Re: Radical fraction
Quote:

Originally Posted by drewm
how would I write 4/√7 with a fraction whose denominator is even?

Thanks

If you think about it another way - you need to multiply top and bottom by $\sqrt{7}$ to rationalise the denominator. However, 7 is not an even number so you must multiply top and bottom by $2$ since multiplying any integer by 2 gives an even number.

Plato did the same thing but combined the steps
• Jul 25th 2011, 05:52 PM
theloser
Re: Radical fraction
$\sqrt7\cdot\sqrt7=\sqrt{7\cdot7}=\sqrt{49}=7$
Like they said add 2 in front of the radical, there you would multiply $7\cdot2$.