Vertex Form of a parabola:
y = a ( x - h)2 + k
where vertex is: (h, k)
In this exercise, vertex is (4, 2), and assuming that a = 1:
h = 4
k = 2
a = 1
The equation of the parabola in Vertex Form is:
y = 1 (x - 4)2 + 2
Standard Form:
y = (x - 4)2 + 2
y = ( x2 - 2 • x • 4 + 42) + 2
y = (x2 - 8x + 16) + 2
y = x2 - 8x + 16 + 2
y = x2 - 8x + 18