Determine the order of differential equation

Question

Solution of differential equation on interval of x values

Solve the following problem:

Determine the order of each differential equation, and whether or not the given functions are solutions of that equation on some interval of x values.

(a) (y')^2 = 4y; Y₁ = X², Y₂ = 2X² , Y₃ = e^-x

(b) Y" +9y =0; Y₁= 4sin3X, Y₂ = 6sin(3X+2)