example20 := (-82*x^3+46*x^2*y-49*x^2-66*x*y^2+18*x*y+16*x-22*y^3+38*y^2-48*y)
/(-39-87*x^3-13*x^2*y-87*x^2-63*x*y^2-31*x*y+90*x+66*y^3+88*y^2+74*y)*((-20*x+
31*y-52)/(37*x-59*y-54))^(1/2)*exp((83-22*x^3+17*x^2*y+63*x^2+21*x*y^2-12*x*y-\
21*x-74*y^3+55*y^2-17*y)/(-62-65*x^3-28*x^2*y-5*x^2+27*x*y^2+26*x+13*y^3+83*y^
2-19*y));