What are the solutions for x when y is equal to 0 in the quadratic function y=x^2-8x

I would use the quadratic formula for this:

  x = -b ± √b² - 4ac over 2a
  x = 8 ± √64 - 4(1)(0) over 2(1)
  x = 8 ± √64 over 2
  x = 8 ± 8 over 2 [simplify]
  x = 4 ± 4
     x1 = 4 + 4    x2 = 4 - 4
     x1 = 8          x2 = 0

Thus, the solutions for x would be 0 and 8.

4hours and 40 mins she would be 120 meters high