[tex]\it a)\ \ x^2-9=0 \Rightarrow x^2=9 \Rightarrow x=\pm3\\ \\ c)\ x^2=0 \Rightarrow x=0\\ \\ e)\ x^2=8 \Rightarrow x=\pm\sqrt8=\pm\sqrt{4\cdot2}=\pm2\sqrt2\\ \\ g)\ \ 5x^2=10\bigg|_{:5} \Rightarrow x^2=2 \Rightarrow x=\pm\sqrt2\\ \\ i)\ \ \underbrace{6x^2}_{\geq0}=\ \underbrace{-1930}_{ < 0} \Rightarrow x\in\O\ \ (ecua\c{\it t}ie\ imposibil\breve a\ \hat\imath n\ \mathbb R)[/tex]
[tex]\it k)\ \ 9x^2+6x=0 \Rightarrow 3x(3x+2)=0 \Rightarrow \begin{cases} \it 3x+2=0 \Rightarrow 3x=-2 \Rightarrow x_1=-\dfrac{2}{3}\\ \\ \it 3x=0 \Rightarrow x_2=0\end{cases}[/tex]
