Leon is flying his plane to Au Gres, Michigan. He maintains a constant altitude until he passes over a marker just outside the neighboring town of Omer, when he begins his descent for landing. During the descent, his altitude, in feet, is given by $$A(x) = 128x^3 - 960x^2 + 8000$$ where $x$ is the number of miles Leon has traveled since passing over the marker in Omer.

1. What is Leon’s altitude when he begins his descent?
   ft
2. Graph $A(x)$ in the window
   $$\begin{aligned} \text{Xmin} \amp = 0 \amp\amp \text{Xmax} = 5\\ \text{Ymin} \amp = 0 \amp\amp \text{Ymax} = 8000 \end{aligned}$$
3. Use the Trace feature to discover how far from Omer Leon will travel before landing. (In other words, how far is Au Gres from Omer?)
   mi
4. Verify your answer to part (c) algebraically.
   $A(5)=$