Tìm x, biết

Bài 1: Tìm x
$$\begin{gathered} \mathrm{a}/ (\mathrm{x}+3)({\mathrm{x}}^2-3\mathrm{x}+9)-\mathrm{x}{(\mathrm{x}-2)}^2=27 \\ \mathrm{b}/ (\mathrm{x}-1)(\mathrm{x}+5)+3=0 \end{gathered}$$