For the graph of a certain quadratic y = ax^2 + bx + c, the vertex of the parabola is (3,7) and one of the x-intercepts is (-2,0). What is the x-coordinate of the other x-intercept?
The points on a quadratic are symetrical around the axix of symetry, which on this paroabola would be the vertical line containg the point (3,7) so the line x=3.
(-2,0) is 5 units away horizontaly from the axis of symetry, so the other x intercept will also be 5 units away, so (3+5,0) or (8,0) is the other x intercept, as shown by the attached graph.
https://www.desmos.com/calculator/qk486go8lu