Homework Help: Square roots and fractions

1. Mar 17, 2008

Ry122

How do you get 3/sqrt2 from 3sqrt2/2?

2. Mar 17, 2008

scarecrow

3. Mar 17, 2008

Math Is Hard

Staff Emeritus
hint: sqrt2/sqrt2 = 1

4. Mar 17, 2008

Ry122

sorry dont follow

5. Mar 17, 2008

Integral

Staff Emeritus
Try going the other way.
$$\frac 3 {\sqrt 2}$$

to get

$$\frac {3 \sqrt 2} 2$$

6. Mar 17, 2008

Feldoh

If you're going from 3sqrt2/2 to 3/sqrt2 you're basically de-rationalizing the denominator.

7. Mar 18, 2008

HallsofIvy

By definition $(\sqrt{2})^2= \sqrt{2}\sqrt{2}= 2$. That means that
$$\frac{\sqrt{2}}{2}= \frac{\sqrt{2}}{\sqrt{2}\sqrt{2}}$$

8. Mar 21, 2008

Air

$\frac{3}{\sqrt 2} . \frac{\sqrt 2}{\sqrt 2} = \frac{3 \sqrt 2}{2}$.

This is rationalising the denominator as you cannot have a surd on the denominator. The question that you are asking is how you get the reverse, de-rationalising the denominator. Try opposite steps to the one I shown.