What is the vertex of this parabola?

Step-by-step explanation:

It is the turning point, (100,0)

The vertex of a parabola is the point at the intersection of the parabola and its line of symmetry

Step-by-step explanation:  it is the center so it would be 100

which expression represents the approximate length of bc?

step-by-step explanation:

5x+40

5(x + 8)

7x - 49

7(x - 7)

18x + 9

9(2x + 1)

15x - 10

5(3x - 2)

step-by-step explanation:

for number one all you have to do is factor 5 out of 5x + 40

for number 2 factor 7 out of 7x - 49

for number three factor 9 out of 18x + 9

for number four factor 5 out of 15x - 10