Find the general solution of the equation

$y^{\text{'}\text{'}}-y^{\text{'}}=(3-3x)e^x-4.$

Find the general solution of the equation

$y^{\text{'}\text{'}}-2y^{\text{'}}+y=e^{x}se{c}^{2}x.$

If the general solution of the differential equation

$y^{\text{'}\text{'}}-3y^{\text{'}}-18y=9sec2x$ is expressed as $y=c_1(x)e^{-3x}+c_2(x)e^{6x},$ then what is $c_1^{\text{'}}{e}^{-3x}-2c_2^{\text{'}}{e}^{6x}?$