Answer:
vertex = (3, 19 )
Explanation:
The equation of a parabola in vertex form is
y = a(x - h)² + k
where (h, k ) are the coordinates of the vertex and a is a multiplier
Using the method of completing the square
add/subtract ( half the coefficient of the x- term )² to x² - 6x
y = x² + 2(- 3)x + 9 - 9 + 28
= (x - 3)² - 9 + 28
= (x - 3)² + 19 ← in vertex form
vertex = (3, 19 )