The x intercepts of a parabola equation are the values of x for which y is equal to zero. These are the points at which the line of the parabola intercepts the x-axis.
To find the x intercepts of a parabola, y must be set equal to zero, as the intercepts are the points where the line meets the x-axis. For example, to find the x intercepts of y = -x^2 - 9, set the equation equal to zero.
x^2 - 9 = 0
(x+3) (x -3) = 0
x = 3
x = -3
The x intercepts of this parabola are the two points on the x-axis, 3 and -3.