![(y-k)^2=4p(x-h)](https://img.qammunity.org/2023/formulas/mathematics/college/a4xwhceyi3lj0pdwnh7r9ws5v5dz36j0p9.png)
The equation above is the standard form equation of a horizontal parabola and have the next caractheristics:
- The vertex is (h,k)
- If 4p > 0, it opens right
If 4p < 0, it opens left
- | p | is the distance from the vertex to the focus
- The directrix is vertical and the vertex is midway betweeen the focus and directrix
- The directrix is 2| p | units from the focus
For the given parabola:
![\begin{gathered} (y+1)^2=12(x-3) \\ \\ k=-1 \\ h=3 \\ 4p=12 \\ p=(12)/(4)=3 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/odhqonppjr3the7jidl2shr24e45xz3thc.png)
Focus coordinates: It has the same y-coordinate that the vertex, the x-coorcdinate is |p| units to the right (as the parabola opens right) from the x-coordinate of the vertex:
![\begin{gathered} \text{focus: } \\ (h+\lvert p\rvert,k) \\ \\ (3+3,-) \\ (6,-1) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/moilf7ya2126z2hyk01dbjk39e7j4ygf3b.png)
Directrix: it is a vertical line as follow (for a parabola that opens right)
![\begin{gathered} \text{Directrix:} \\ x=h-\lvert p\rvert \\ \\ x=3-3 \\ x=0 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/2ghpnm931774szs5g7mjskcm04ok09jrv4.png)
The vertex of the parabola is (3, -1). The parabola opens right, and the focus is 3 units away from the vertex. The directrix is 6 units from the focus. The focus is the point (6, -1). The directrix of the equation is x=0