### Home > CALC > Chapter 8 > Lesson 8.1.4 > Problem 8-44

8-44.

Since the distance function tracks the height of the shell, and the shell was launched from the top of the hotel,where was the shell at *t* = 0?

You could take the derivative and evaluate at *t* = 0.

Or you could deconstruct the position function:

Notice that the distance function is a parabola. Use Algebra or Calculus to find the *x*-value of the vertex of this parabola.

Recall that a local maximum (or local minimum) is a *y*-value, not an *x*-value. After all, max and min mean highest and lowest, which are vertical measurements (*y*-axis measurements).

Given that *s*(0) ≠ 0, is it reasonable to assume that the ground is located at *s*(*t*) = 0?