[tex]2x^{2}-8x=0\\\\2x(x-4)=0\\\\2x=0\\\\x=0\\\\x-4=0\\\\x=4\\\\\\x_{1}=0\\\\x_{2}=4[/tex]

[tex]3x^{2}-27=0\\\\3(x^{2}-9)=0\\\\3(x-3)(x+3)=0\\\\(x-3)(x+3)=0\\\\x-3=0\\x=3\\\\x+3=0\\x=-3\\\\\\x_{1}=-3\\\\x_{2}=3[/tex]

[tex]-5x^{2}+10=0\\\\-5(x^{2}-2)=0\\\\x^{2}-2=0\\\\x^{2}=2\\\\x_{1}=\sqrt{2} \\\\x_{2}=-\sqrt{2}[/tex]