Which of the following equations is of a parabola with a vertex at (0, -5)? y = (x - 5)2 y = (x + 5)2 y = x2 - 5 y = x2 + 5

Put 0 for x in each possible choice and see which one gives you y = -5.

The appropriate choice is
  y = x² - 5


Of course, you know the vertex form is
  y = a(x -h)² + k
for vertex (h, k) and scale factor "a".
Then for (h, k) = (0, -5), this is
  y = ax² -5
Only one choice matches that: y = x² -5. (for a=1)