Finding Thevenin equivalent between points AB with dependent current source

[erezb84]

Homework Statement

I need to find the thevinin equivalent for points AB.

The Attempt at a Solution

I know the Is current is splitting equally between R1 and R3, but doesn't go to R2 because of the dependent current source.
so i thought that through:
I(R5) = Is
and I(R3)=Is/2
so the Vab=-3/2*IS*R
but this is wrong.
where is my mistake?
thanks!

 

[rude man]

1. Let I_g = 0, put V₁ across R_Land compute i. Then thevenin R_eq = V₁/i.

2. Restore I_g, compute V across R_L. Thevenin current source then is V/R_eq.