Given a quadratic equation
[tex]ax^2+bx+c=0[/tex]
the quadratic formula states that the solutions are
[tex]x_{1,2}=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}[/tex]
Plug your values to get
[tex]x_{1,2}=\dfrac{-(-7)\pm\sqrt{(-7)^2-4\cdot 1 \cdot (-6)}}{2\cdot 1}[/tex]
Which evaluates to
[tex]\dfrac{-(-7)\pm\sqrt{(-7)^2-4\cdot 1 \cdot (-6)}}{2\cdot 1} = \dfrac{7\pm\sqrt{73}}{2}[/tex]
So, the two solutions are
[tex]x_1 = \dfrac{7+\sqrt{73}}{2},\quad x_2 = \dfrac{7-\sqrt{73}}{2}[/tex]