The x-axis is the line y=0, so the roots of the quadratic are where the parabola cuts the x-axis, the x-intercepts. x=(-9±√81+12)/6=(-9±√93)/6. (The y-intercept is given by putting x=0: y=-1.)
The x-intercepts are at (0.1073,0) and (-3.1073,0) approx.