(b) Determine the vertex, the x - intercepts, and the y -intercept of the graph of y=-x2 -8x-7. Sketch the graph of this parabola. H -10 -9 -8 -7 -6 -5 -4 -3-2 -1 2 3 4 5 6 7 (10 pts) 4. Solve the following quadratic equations. If the solutions are imaginary, write them in the form a +bi. (a) x - 6.x+5=0 (b) x +4=0