求助标题五个字

其实2阶，可变成1阶
(x-1)y''-xy' +y =0
(x-1)(y''-y') -(y'-y) =0
(y''-y') -[1/(x-1)](y'-y) =0
[1/(1-x)]{(y''-y') -[1/(x-1)](y'-y)} =0
d/dx [ (y'-y)/(x-1) ] =0
(y'-y)/(x-1) = C1
y'-y= C1(x-1)
e^(-x).[y'-y]= C1(x-1)e^(-x)
d/dx [e^(x).y] = C1(x-1)e^(-x)
e^(x).y
=∫C1(x-1)e^(-x) dx
=-∫C1(x-1) de^(-x)
=-C1.(x-1)e^(-x) +C1.∫e^(-x) dx
=-C1.(x-1)e^(-x) -C1.e^(-x) +C2
=-C1.xe^(-x) +C2
y=-C1.x +C2.e^x + C3