Section $2\mathrm{.}2($p$.48-50)$

$5.$ Problem $2\mathrm{.}2\mathrm{.}8$: Solve $e^{x}y\frac{dy}{dx}=e^{-y}+e^{-2x-y}$

$6.$ Problem $2\mathrm{.}2\mathrm{.}12$: Solve $sin3xdx+2yco{s}^{3}3xdy=0$

Section $2\mathrm{.}3($p$.57-59)$

$7.$ Problem $2\mathrm{.}3\mathrm{.}4$: Solve $3\frac{dy}{dx}+12y=4$

$8.$ Problem $2\mathrm{.}3\mathrm{.}6$: Solve $y^{\text{'}}+2xy=x^3$

$9.$ Problem $2\mathrm{.}3\mathrm{.}19$: Solve $(x+1)\frac{dy}{dx}+(x+2)y=2x{e}^{-x}$