Pratap-Pg.no.188,Ex.no.2)

code_begins

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))

code_ends

Solution by:
- < VINAY >, < STUDENT >, < Symbiosis >
- <Your Name>, <Profession>, <Organization>