Vertex of a parabola exists at:
[tex]( \frac{-b}{2a},y( \frac{-b}{2a})) [/tex]
b = coefficient of x term = -4
a = coefficient of squared term = 1
So,
[tex] \frac{-b}{2a}= \frac{4}{2}=2 [/tex]
and
[tex]y(2)=(2)^{2}-4(2)+1=-3 [/tex]
Therefore, the vertex occurs at (2, -3)
Thus the correct answer is option D
