it works after i delete the constraints A == B ; // previously from your quadratic equation.
i think i need to think about a input system of (xp,yp) and (xp1,yp1) and from there calculate the display.
having some problem displaying x = 0 , x = -3 etc.
i think it is a bit harder than simply downgrading from a quadratic equation display.
need to think more!!