example4 := (-85-46*x^3-33*x^2*y+87*x^2-34*x*y^2+40*x*y+77*x+y^3-10*y^2-65*y)/
(50+54*x^3+18*x^2+52*x*y^2+36*x*y+91*x-22*y^3+51*y^2-27*y)*exp((-31+60*x^2-91*
x*y-47*x-97*y^2-2*y)/(10+25*x^2+31*x*y-27*x+65*y^2+88*y));