Solving differential equation y "+ 9y = sin3x Thank you very much. Let's go back quickly. The answer is y = c1sin3x + c2sin3x-1 / 6xsin3x

Solving differential equation y "+ 9y = sin3x Thank you very much. Let's go back quickly. The answer is y = c1sin3x + c2sin3x-1 / 6xsin3x

In the method of variation of constants, the first solution is y '' + 9y = 0, and the characteristic equation is T & sup2; + 9 = 0t = ± 3I, then the general solution is y = c1cos3x + c2sin3x. Now let y '' + 9y = sin3x be the solution of y = f (x) cos3x + G (x) sin3x, and let y '= f (x) [cos3x]' + G (x) [sin3x] ', then f' (x) cos3x +