8.2.1.15 Differential Equations

Condition: The operating method solve the problem of Koshi. \ [\ begin {array} {l} y^{\ prime \ prime} -2 y^{\ prime}+y = -12 \ cos 2 x-9 \ sin 2 x \\ y (0) =-2, \ quad y^{\ prime} (0) = 0 \ end {array} \]