# Thread: Radical fraction

1. ## Radical fraction

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

Thanks

2. ## Re: Radical fraction

Originally Posted by drewm
how would I write 4/√7 with a fraction whose denominator is even?
$\frac{8\sqrt 7}{14}$

3. ## Re: Radical fraction

ok thanks, but can you tell me how you got that?

4. ## Re: Radical fraction

Originally Posted by drewm
ok thanks, but can you tell me how you got that?
I multiplied numerator and denominator by $2\sqrt 7~.$

5. ## Re: Radical fraction

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

6. ## 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 $7\cdot2$.