Question 153694
when the graph crosses the x-axis (x-intercept), the value of y is zero
__ this happens when x+3=0 or x-5=0


so the x-intercepts are -3 and 5


the x-coordinate of the vertex is midway between the intercepts (on the axis of symmetry)
__ midway between -3 and 5 is 1 ([5-3]/2)


substituting 1 for x in the equation gives y=(1+3)(1-5) or y=-16


so the vertex is at (1,-16)