Hey guys,(adsbygoogle = window.adsbygoogle || []).push({});

Been struggling with this all day. I've got the following situation:

x1*=-x1+x2

x2*=-2x1-x2

Where the 1&2 after the x are subscripts.

Now i can find the equilibrium no trouble: (0,0). I also know, by looking at the eigenvalues that it is a sink.

But how on earth do you sketch it? I've found nullclines:

-x1+x2 = 0

-2x1-x2 = 0

But i cannot, for the life of me, tell which way these lines are going.

Help really appreciated.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Help me learn to sketch phase portraits!

**Physics Forums | Science Articles, Homework Help, Discussion**