Solution
= Solution
Factor each component of the <vector field>. The horizontal-velocity <nullclines> and vertical-velocity <nullclines> are, respectively,
$$
\boxed{\dot x=0:\ x=0,\ y=1,\ x+y=1;\qquad
\dot y=0:\ y=0,\ xy=2.}
$$
The last curve is a <hyperbola>. In the nonnegative quadrant its branch is $y=2/x$ for $x>0$.