Which of the following are partial differential equations I

Which of the following are partial differential equations? I. y\" + y = 0 II. xy\' + 4y = 0 III. d^2 y/dx^2 - 4y (dy/d pi) + x^2 y - d^3 y/dx^3 a) II, IV b) None of these. c) III d) I e) I, II, III, IV

Solution

All the equations are Ordinarey differential equations

I . 2 nd order DE with constant coefficient .

II . I order linear DE

III . 3rd order DE . IV . I order DE

ANS b. none of these