[tex]y=6x^2+24x-192\\\\y=0\ \ \ \Leftrightarrow\ \ \ 6x^2+24x-192=0\ /:6\\\\x^2+4x-27=0\\\\x^2+2\cdot2\cdot x+2^2-2^2-27=0\\\\(x+2)^2-31=0\\\\(x+2)^2=31\ \ \ \Leftrightarrow\ \ \ (x+2= \sqrt{31} \ \ \ or\ \ \ x+2=- \sqrt{31})\\\\x=-2+ \sqrt{31}\ \ \ or\ \ \ x=-2- \sqrt{31}[/tex]
