Fractions in Einstein Relativity Theory

1. Feb 20, 2009

Norway

1. The problem statement, all variables and given/known data
From the formula $$t = \frac{L}{v+c} + \frac{L}{v-c}$$ I've made $$t = \frac{2L}{c}\left(\frac{1}{1 - \frac{v^2}{c^2}}\right)$$. This is the problem:
$$\left(\frac{1}{1 - \frac{v^2}{c^2}}\right) = \left(\frac{1 + \frac{v^2}{c^2}}{1 - \left(\frac{v^2}{c^2}\right)^2}\right)$$
How?

2. Relevant equations
That's kinda what I'm asking for. :-b

3. The attempt at a solution
I've gotten this far, but no more. I've tried to see how they relate, but I can't figure anything out.

2. Feb 20, 2009

George Jones

Staff Emeritus
Factor the difference of squares in the denominator.

3. Feb 20, 2009

xboy

You remember what $$x^2 - y^2$$ equals to?

4. Feb 20, 2009

Norway

I get it. Thanks so much! Kinda embarrassing. :-b