Question

1. Show that y = 4 sin 3x is a solution of the differential eequation d^2y/dx^2 + 9y =0

Answer 1

Answer:

$\frac{dy}{dx \: } = 4 \times 3cos3x = 12cos3x \\ again \: diff \: w \: r \: t \: x \\ \frac{ {d}^{2} y}{ {dx}^{2} } = 12 \times ( - 3sin3x) = - 36sin3x = - 9(4sin3x) \\ = - 9y \\ \: \frac{ {d}^{2}y }{ {dx}^{2} } + \: 9 y = 0$

Answer 2

Answer:

this is correct........................................