\(a,\left(x-3\right)^{x+2}=\left(x-3\right)^{x+12}\\ \Leftrightarrow\left(x-3\right)^{x+2}\left[1-\left(x-3\right)^{10}\right]=0\\ \Leftrightarrow\left[{}\begin{matrix}x-3=0\\x-3=1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\\ b,\left|x+2\right|=\dfrac{1}{2}-2x\Leftrightarrow\left[{}\begin{matrix}x+2=\dfrac{1}{2}-2x\left(x\ge-2\right)\\x+2=2x-\dfrac{1}{2}\left(x< -2\right)\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}3x=-\dfrac{3}{2}\left(x\ge-2\right)\\x=\dfrac{5}{2}\left(x< -2\right)\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\left(tm\right)\\x=\dfrac{5}{2}\left(ktm\right)\end{matrix}\right.\\ \Leftrightarrow x=-\dfrac{1}{2}\)