1. The problem statement, all variables and given/known data "Vary the following actions and write down the Euler-Lagrange equations of motion." 2. Relevant equations [itex]S =\int dt q[/itex] 3. The attempt at a solution Someone said there is a weird trick required to solve this but he couldn't remember. If you just vary normally you get [itex]\delta S=\int dt \delta q=0[/itex] and thats not helpful. Any suggestion on how to avoid this problem?