Finding equation for Hyperbola, given 3 points. 
"A hyperbola passes through $(0,-1)$, $(2, -1.5)$ and $(-1, 0)$. Find its equation..."

How would I go working this out? Would the $x$ and $y$ asymp be $-1$?  
I dont just want an answer, coz I need to know how to do it
Thanks.

Judging from this article and this random example I tried, you would need at least $5$ distinct points to uniquely determine a hyperbola.
What I can tell you is that, because the slope between $(-1,0)$ and $(0,-1)$ is steeper than between $(0,-1)$ and $(2,-1.5)$, the hyperbola will probably take the form of $$\frac{(x-x_0)^2}{a^2} - \frac{(y-y_0)^2}{b^2} = 1$$ where $(x_0,y_0)$ is the intersection of the asymptotes whose slopes are $\displaystyle \pm \frac{b}{a}$.
The circle is the only conic uniquely determined by $3$ different points. Everything else needs at least $5$. See this and this and this as examples of why $4$ points is still not enough.
