Which function has a vertex on the y-axis? f(x) = (x – 2)2 f(x) = x(x + 2) f(x) = (x – 2)(x + 2) f(x) = (x + 1)(x – 2)

The vertex has its x-coordinate halfway between the roots (x-intercepts). The x-intercepts are ...
  (x-2)² . . . . . +2 (multiplicity 2) . . . vertex is x=2
  x(x+2) . . . . . 0 and -2 . . . vertex is x=-1
  (x-2)(x+2) . . . -2 and +2 . . . vertex is x = 0, the y-axis
  (x+1)(x-2) . . . -1 and 2 . . . vertex is x=1/2

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