I am looking at the equilibrium points of the following system:
$$ X' = a_1 X - a_2 X^2 -a_3 XY \\ Y' = \beta a_3YX-a_4Y-a_5Y^2 $$
I found the following $(X,Y)$ equilibrium points
$(0,0); \ (\frac {a_1}{a_2},0 ); \ (0,-\frac{a_4}{a_5})$ but I can not find the 4th equilibrium point when both $X\ne 0$ and $Y \ne 0$. I get lost in computation and cant find the solution.