depends([h,theta,h1,theta1],t); eqns:['diff(h,t)+l*cos(theta)*'diff(theta,t) = -(diff('h1,t)+l*cos(theta)*'diff(theta1,t)), 1/2*m*'diff(h,t)+1/2*I*'diff(theta,t) = 1/2*m*'diff(h1,t)+1/2*I*'diff(theta1,t)]; vars:['diff(h1,t),'diff(theta1,t)]; solve(eqns,vars),ratsimp;