The distance the bicycle travels and the time taken are expressed by the formula d(t)=t^2-2t, there d(t) is in miles and t in hours. Find the time taken by the bicycle to cover a distance of 63 miles.

Answer 1

just plug in the numbers:

63 = t^2 - 2t
t^2 - 2t - 63 = 0
(t-9)(t+7) = 0

so, t=9 or -7

Since negative time does not correspond to any known reality, use t=9.

Check:
9^2 - 2*9 = 81-18 = 63