math
posted by ibob .
The position function of a spaceship is below and the coordinates of a space station are (8, 5, 11). The captain wants the spaceship to coast into the space station. When should the engines be turned off?
r(t) = (5+t)i + (3+ln(t))j + (9  4/(t^2) +1

I noticed that you have unbalanced parentheses in the (9  4/(t^2) + 1 part.