\(a,\Leftrightarrow x^2-4x+4-x^2+9=-3\\ \Leftrightarrow-4x=-16\Leftrightarrow x=4\\ b,\Leftrightarrow\left(x+1\right)\left(2x-3\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=\dfrac{3}{2}\end{matrix}\right.\\ c,\Leftrightarrow x^2-3x-4x+12=0\\ \Leftrightarrow\left(x-3\right)\left(x-4\right)=0\Leftrightarrow\left[{}\begin{matrix}x=4\\x=3\end{matrix}\right.\\ d,\Leftrightarrow x^2\left(x+3\right)-4\left(x+3\right)=0\\ \Leftrightarrow\left(x-2\right)\left(x+3\right)\left(x+2\right)=0\Leftrightarrow\left[{}\begin{matrix}x=2\\x=-3\\x=-2\end{matrix}\right.\)
c: \(\Leftrightarrow\left(x-3\right)\left(x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\)
