For what values of the nonnegative constant a in the equation y + y = 0 do

For what values of the nonnegative constant a in the equation y" + λy = 0 do thereexist nonzero solutions satisfying the boundary condi-tions in Problems a-b? The values of a are called eigenvaltions and the corresponding solutions are called eigenfunctions.
(a) y(0) = 0, y(π) = 0
(b) y'(0) = 0, y(π) =0