\(a,\Rightarrow\left(x-3\right)\left(5x-1\right)=0\Rightarrow\left[{}\begin{matrix}x=3\\x=\dfrac{1}{5}\end{matrix}\right.\\ b,\Rightarrow x^3+5x^2-3x^2-15x+2x+10=0\\ \Rightarrow\left(x+3\right)\left(x^2-3x+2\right)=0\\ \Rightarrow\left(x+3\right)\left(x-2\right)\left(x-1\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=-3\\x=1\\x=2\end{matrix}\right.\\ c,\Rightarrow\left(9x^2-18x+9\right)+\left(y^2-6y+9\right)+\left(2z^2+4z+2\right)=0\\ \Rightarrow9\left(x-1\right)^2+\left(y-3\right)^2+2\left(z+1\right)^2=0\\ \Rightarrow\left\{{}\begin{matrix}x-1=0\\y-3=0\\z+1=0\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=1\\y=3\\z=-1\end{matrix}\right.\)
