The quadratic equation is (for ax2 + bx + c = 0), x = (-b + sqrt(b2 - 4ac))/2a
In this case a = 1, b = 6, and c = -7
Plug them in and simplify. You should get x = 1 and x = -7 but of course, you need to show all the steps.
If you need help, let me know