Quadratic Equations - Super Mario Brothers

Help Mario stomp the Koopa Trooper. Select the correct values of a and b in the equation so that he can successfully land on the Koopa.
Instructions for use: Select the values of a and b that you think will hit the target. Then press 'Make Mario Jump'. Once Mario lands press 'Stop Mario Jump' before altering your estimates. Press 'Return Mario' to put Mario back at the start. Press 'Remove Trace' to remove the trace (this can be pressed at anytime) Press 'New Target' to get a new target to jump on. Press 'Hide Instructions' to hide the instructions.