Question

find d^2y/dx^2 1-xy=x-y

Answer 1

1-(x*y'+y)=1-y'
0-(x*y"+y'*1+y')=0-y"

Answer 2

y'=dy/dx
y"=d^2y/dx^2

Answer 3

xy"+y'+y'=y"
xy"+2y'=y"
xy"-y"=-2y'
y"(x-1)=-2y'
y"=(-2y')/(x-1)