已知一个LTI系统的差分方程为：

y[n]-1.143*y[n-1]+0.4128*y[n-2]=0.0675*x[n]+0.1349*x[n-1]+0.0675*x[n-2]

初始条件y(-1)=1,y(-2)=2，输入x(n)=u(n)，计算系统的零输入响应

-known LTI system of a differential equation : y [n] -1.143 * y [n-1] 0.4128 * y [n-2] x = 0.0675 * 0.1349 [n] * x [n -1] 0.0675 * x [n-2] initial conditions y (1) = 1, y (2) = 2, input x (n) = u (n), we calculate the zero input response