# Homework Help: Can someone show me how this is solved algebraically

1. Oct 8, 2012

### chris_0101

1. The problem statement, all variables and given/known data
I need to show how the first equation gives the second equation algebraically

2. Relevant equations

I've tried multiple methods such as rationalizing the denominator with no avail.

3. The attempt at a solution

Any help will be greatly appreciated,

Thanks.

2. Oct 8, 2012

### Zondrina

Multiply out the numerator of that mess over c^2. Then find a quick common divisor. Then use the rules :

$\sqrt{\frac{a}{b}} = \frac{\sqrt{a}}{\sqrt{b}}$

and

$\frac{\frac{a}{b}}{\frac{c}{d}} = \frac{ad}{bc}$

3. Oct 8, 2012

### chris_0101

I'm not sure what you mean by "multiply out the numerator of that mess over c^2"?

4. Oct 8, 2012

### Zondrina

The quantity $(\frac{u'+v}{1+vu'/c^2})^2$

5. Oct 8, 2012

### chris_0101

yea, but how does one multiply out the numerator?
do you mean like this:
(a/b)/c = (a/b)*(1/c)

6. Oct 8, 2012

### Zondrina

...

$(\frac{u'+v}{1+vu'/c^2})^2 = (\frac{u'+v}{1+vu'/c^2})(\frac{u'+v}{1+vu'/c^2})$

Now some simple bedmas and you're done....

7. Oct 8, 2012

### chris_0101

This is what I got:

(u'^2 + 2u'v + v^2)/((u'^2 v^2)/c^4) + (2((u'v)/c^2) +1

Is this right?

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook