The graph of a quadratic function is a parabola.
The axis of symmetry of a parabola is a vertical line that divides the parabola into two congruent halves. The axis of symmetry always passes through the vertex of the parabola. The x coordinate of the vertex is the equation of the axis of symmetry of the parabola.
Taking into account the definition above, then the other intersection with x will be:
horizontal distance between the axis of symmetry and intersection with x:
d = 7 - (- 1) = 7 + 1 = 8
The second intersection will then be:
x2 = -1-8 = -9
Answer:
the other x-intercept is:
x2 = -9