One has to create a table containing values of the coordinates x and y to plot a curve in Excel. This plot used smoothing to improve its appearance.
One can right click the chart and use "Select Data..." in the drop down menu to specify the horizontal and vertical data for the curve's series. One can also click on the axes and series to "format" the appearance of the chart. The only real solution for the cubic equation is x=-1.22249 as previously shown.
Supplemental (Feb 6): The axes are incorrectly labeled on the chart. horizontal is x and vertical is y.