Stuck on Real Gas Problem Derivatives?

[krootox217]

Homework Statement

The task is the following:

Homework Equations

The Attempt at a Solution

I calculated the derivatives for Vm (crit) and set them = 0, but somehow I can't solve the equation to obtain Vm (crit) on one side alone.

This is how far i managed to do it:

Can someone help me?

 

[TSny]

One approach: For each equation move the second term on the left to the right side. Then divide the two equations.

 

[krootox217]

Wow, thanks!

I totally forgot that method