no online info unfortunatly...and the labs I do in class are in french... care to try ? A friend gave me clues and I was finally able to do the problem...want to know how ? >restart: with(plots): with(linalg): >f:=(x,y)->(-3*x^2-y^2); >bla:=plot3d(f(x,y),x=-2..2,y=-2..2,view=[-2..2,-2..2,0..1],axes=framed,style=wireframe): >display(bla); >gradient:=((diff(f(x,y),x),diff(f(x,y),y))); >subs(x=1,y=3/2,vector[gradient]]); >trajectory:=diff(y(x),x)=gradient[2]/gradient[1]; >dsolve(diff(y(x),x)=y(x)/(3*x),y(x)); >dsolve({diff(y(x),x)=y(x)/(3*x),y(1)=3/2},y(x)); >x[a]:=t; >y[a]:=3*t^(1/3)/2; >plot([x[a],y[a],t=0..1]); >ble:spacecurve([x[a],y[a],f(x[a],y[a])],t=0..1,color=pink,thickness=3): >bli:spacecurve([x[a],y[a],0],t=0..1,color=orange,thickness=3): >blo:spacecurve(sqrt(ln(1/0.4)/3)*cos(t),sqrt(ln(1/0.4))*sin(t),0.4],t=0..2*Pi,color=blue,thickness=3): >display(bla,ble,bli,blo); I you need any explanations, tell me