21. What are the vertex, focus, and directrix of the parabola with equation y=-6x +15?
vertex: (3,6)
focus: (3, 6.25)
directrix: y = 5.75
vertex: (-6, 3)
focus: (-6, 3.25)
directrix: x = 2.75
vertex: (3,-6)
focus: (3,-5)
directrix: y = -7
vertex: (3,-6)
focus: (3.25, -6)
