(a) y = a cosx +b sin x is the solution of the differential equation
(i) \(\frac{d^2y}{dx^2} + y = 0\)
(ii) \(\frac{d^2y}{dx^2} - y = 0\)
(iii) \(\frac{dy}{dx} + y = 0\)
(iv) \(\frac{dy}{dx} + x\frac{dy}{dx} = 0\)
(b) Find the solution of the differential equation
\( x\frac{dy}{dx} + 2y = x^2 , (x≠0)\) given that y = 0 When x = 1