function y = x4dot_lin(x)
g=10; % gravitasi
l=0.28; % panjang pendulum
M=0.11; % massa kereta
m=0.03; % massa pendulum
x3=x(1);
x4=x(2);
u=x(3);
A=0;
B=(M+m)*g*x3;
C=u;
D=m*l;
E=(M+m)*l;
y=(A-B+C)/(D-E);