Question

if the zeros of a quadratic function , f, are -3 and 5, what is the x-coordinate of the vertex of the function f?

Answer 1

we know function "f" has zeros at -3 and 5, namely x = -3 and x = 5, well for a quadratic, the vertex is half-way between those two zeros,

-3................... 1....................5

so the x-coordinate is at 1.  Check the picture below, regardless of the shape of the parabola.