典型常系数线性齐次方程：特征方程：r^4+r^3+r+1=0r^3(r+1)+r+1=0(r+1)(r^3+1)=0(r+1)(r+1)(r^2-r+1)=0r1=-1 r2=-1 r3=1/2+i根3/2 r4=1/2-i根3/2通解为：y=(c1x+c2)e^(-x)+{c3cos[(根3)x/2]+c4sin[(根3)x/2]}e^(x/2)
