Where does that StartFraction ... mess come from? -- I've seen it in other questions.
[tex] x = \dfrac{- -10 \pm \sqrt{(-10)^2 - 4(7)(-2)}}{2(7)}[/tex]
Comparing that to the general quadratic formula
[tex] x = \dfrac{-b \pm \sqrt{b^2-4ac}}{2a}[/tex]
we see b=-10 (agreeing in both places) a=7 (two places), c=-2
Answer: 7x² - 10x - 2 = 0
