The vertex form of a parabola is:

y = a(x - h)^2 + k, where(h,k) is the vertex and is constant.

In our case the vertex is (-1,-108) that is h = -1 and k = -108. We plug the values for h and k into the equation:

y =a(x+1)^2 -108

Next we use y-intercept (0,-105) to find a:

-105 = a(0 + 1)^2 - 108

a - 108 = -105

a = -108 + 105

a = 3

The equation of the parabola is:

y = 3(x+1)^2 -108

To find the x-intercept we plug x = 0 to find y:

y = 3(0 + 1)^2 - 108

y = -105

The y-intercept is (0, -105)

click here to see the graph for y = 3(x+1)^2 -108