im practising separation of variables for partial differential equations. i came across this site which says:
2. Separation of Variables
'NOTE: In this variables separable section we only deal with first order, first degree differential equations.'
so , if i have a second order or above PDE, then i cant use separation of variables?
i thought one can use separation of variables for example in the wave equation!! that is a second order PDE....
ok im confused
can anyone help me out?
i hope i am clear with this question problem
thank you all very much