How to graph a parabola #y=x^(2)-2x-15#?
You have two choices
1. complete the square to get standard form, find vertex and 2 other points.
2. Use the equation
Complete the square...
find two more points, use x-values near the vertex.
(0, -15) and by symmetry (2, -15) and (-1, -12).
You need to calculate 2 more points as above.