Answer:
(- 5, - 28 )
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
To obtain this form use the method of completing the square
add/subtract ( half the coefficient of the x- term )² to x² + 10x
f(x) = x² + 2(5)x + 25 - 25 - 3
= (x + 5)² - 28 ← in vertex form
with (h, k) = (- 5, - 28)
Vertex = (- 5, - 28 )