sage: x,y,z=var('x,y,z')
sage: contour_plot(-1/2*x**2+x*y+y**2,(x,-5,5),(y,-5,5))
<html><font color='black'><img src='cell://sage0.png'></font></html>

Pratap-Page no.188,Ex.no.2) (last edited 2010-12-18 05:44:12 by V.junghare)