a) \(Q\left(x\right)=x^2+x=0\)
\(\Leftrightarrow x\left(x+1\right)=0\\\Rightarrow \left[{}\begin{matrix}x=0\\x+1=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)
b) \(N\left(x\right)=x^2-4=0\)
\(\Leftrightarrow x^2=4\\ \Leftrightarrow x=\pm2\)
c) \(H\left(x\right)=8-3x=0\)
\(\Leftrightarrow-3x=-8\\ \Leftrightarrow x=\dfrac{8}{3}\)
d) \(g\left(x\right)=x^2-3x=0\)
\(\Leftrightarrow x\left(x-3\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=0\\x-3=0\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=3\end{matrix}\right.\)
