# Math Help - Rydberg Formula (subtracting: 1-1/infinity)

1. ## Rydberg Formula (subtracting: 1-1/infinity)

So I'm using the Rydberg formula in my Astronomy class but I am really confused as to how I am supposed to subtract 1-1/infinity and get a numerical answer without exponents. I understand how the formula works, but I have been out of math classes for so long that I have actually forgot how to do this. If anyone can help me out a little, I would greatly appreciate it.

Thanks!

2. ## Re: Rydberg Formula (subtracting: 1-1/infinity)

You want the limit:

$\lambda=\lim_{n_2\to \infty}R\left(\frac{1}{n_1}-\frac{1}{n_2}\right)=R\left(\frac{1}{n_1} - 0\right)=$ ...

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