Which statements regarding the vertex of a quadratic function are true? select all that apply.
it is the point at which the function has a minimum or a maximum.
it is the point at which the function crosses the r-axis.
it is the point at which the function crosses the y-axis.
it is the point at which the extreme value occurs.
it is the point at which the x-coordinate is zero.
it is the point at which the y-coordinate is zero.