�Note
1 We shall prefer to use the following notations for derivatives:
2
3
2
3
,
,
dy
d y
d y
y
y
y
dx
dx
dx
′
′′
′′′
=
=
=
2 For derivatives of higher order, it will be inconvenient  to use so many dashes
as supersuffix therefore, we use the notation yn for nth order derivative 
n
d yn
dx 9