y = x^2 + 6x + 9
y = (x^2 + 6x) + 9
y = (x + 3)^2 - 9 + 9
y = (x + 3)^2
Thus, the vertex is at x = -3.
When x = -3, y = 0
This means that the vertex is (-3,0).
Note that the vetex is also the only x-intercept.
On the y-axis, x = 0.
When x = 0, y = 9
Thus, the y-intercept is (0,9).