\(a,\Leftrightarrow\left(x+3\right)\left(x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=1\end{matrix}\right.\\ b,\Leftrightarrow x\left(x+5\right)^2=0\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)
a, \(x.\left(x+3\right)-x-3=0\)
\(\Rightarrow x.\left(x+3\right)-\left(x+3\right)=0\)
\(\Rightarrow\left(x+3\right).\left(x-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x+3=0\\x-1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-3\\x=1\end{matrix}\right.\)
b, \(x^3+10x^2+25x=0\)
\(\Rightarrow x.\left(x^2+10x+25\right)=0\)
\(\Rightarrow x.\left(x+5\right)^2=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x+5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=-5\end{matrix}\right.\)
