[tex]8x^2=56\ /:8\\x^2=7\\x^2-7=0\\(x- \sqrt{7} )(x+ \sqrt{7} )=0\\x-\sqrt{7}=0\ \ \ \ \ or\ \ \ \ \ x+\sqrt{7}=0\\x=\sqrt{7}\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x=-\sqrt{7}\\ \\ x\approx2.65\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ x-\approx2.65[/tex]
