SPACE MATH @ NASA | Rotation Velocity of a Galaxy

Stars orbit the center of a galaxy with speeds that decrease as their orbital distances increase. 

A simple function, $V(x)$ can model the orbital speeds of stars as a function of their distance, $x$, from the nucleus of the galaxy:  

$V(x)= \dfrac{350x}{(1+x^2)^{ \frac{3}{4}}}$.

For example: 

At a distance of $10,000$ light years from the center, $x = 1.0$ and the rotation speed is $V(1.0) = 208$ kilometers/sec.

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