Mathcad doesn't need a lot of data to draw curves, as long as there are equations. As you said, the equation 2x 2+y 2+2xy+2x = 0, and the variable range of X must be set in the panel and in front of the curve. It seems that no other mathematical software can directly display the curve by inputting any equation. The equation has variables, and the variables have ranges, which must be set. ...