Determine the approximate maximum distance

Question

y=-0.01x2 +0.7x+6.1

Answer 1

-100 y = x^2 -70 x - 610

x^2 - 70 x = -100 y + 610

x^2 - 70 x + 1225 = -100y + 1835

(x-35)^2 = -100 y + 1835
vertex at x = 35
then y =18.35