Answer:
x = - 7
Step-by-step explanation:
The vertex form of a parabola is
y = a(x - h)² + k
where (h, k) are the coordinates of the vertex and a is a multiplier
y = - (x + 7)² - 10 ← is in vertex form
with h = - 7 since - (- 7) = + 7
vertex = (- 7, - 10 ) with x- value - 7
