6 Complete the following statements to summarize the relationship between the a and k values in the quadratic function rule y ax k and the parabola that is the function s graph the parabola stretches vertically k 0 the parabola compresses vertically the vertex shifts up the y axis a When the a value is positive b When the a value is negative c When the a value increases d When the a value decreases 0 k the parabola opens upward e When the k value increases f When the k value decreases g The vertex of the parabola has coordinates the vertex shifts down the y axis the parabola opens downward