特征方程 4r^2 +4r +1=0,r1=r2=-1/2基本解组:e^(-x/2 ),x*e^(-x/2 )这就是两个线性无关解.通解 y=c1*e^(-x/2 )+c2*x*e^(-x/2 )=(c1+c2*x)e^(-x/2 )y'=c2*e^(-x/2 )-(1/2)(c1+c2*x)e^(-x/2 )=(1/2)(2c2-c1-c2*x)e^(-x...