Hi,
7x²-2x-8=0, so a = 7, b= - 2, and c = -8.
You just need to apply the formula for square equations:
[tex]x_{1,2}=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}=\dfrac{-(-2)\pm\sqrt{(-2)^2-4\cdot 7\cdot (-8)}}{2\cdot 7}=\dfrac{2\pm\sqrt{228}}{14}=\dfrac{2\pm\sqrt{4\cdot 57}}{14}=\\\\=\dfrac{1\pm\sqrt{57}}7\Rightarrow x_1=\dfrac{1-\sqrt{57}}7,\;and\;x_2=\dfrac{1+\sqrt{57}}7.[/tex]
Green eyes.
