Question: Simple solve on equations

restart;

eq1 := xdot = (xk - xk1)/dt;
eq2 := xdot2 = (xk - 2*xk1 + xk2)/dt^2;
eq3 := c*xdot + k*xk + m*xdot2 = F;
sol := solve({eq1, eq2, eq3}, xk);

What am I missing here? Ty 
 

Please Wait...