
Optimization Problem
I'm really confused on this problem(Thinking)[GVIDEO][/GVIDEO]
A company wishes to run a utility cable from point A on the shore to an installation at point B on the island. The island is 6 miles from the shore (point O) It costs $3000 per mile to run the cable on land and $5000 per mile underwater. Assume that the cable starts at A and runs along the shoreline, then angles and runs underwater to the island. Let x represent the distance from O at which the underwater portion of the cable begins, and the distance between A and O be 9 miles.
1. Write the total cost C as a function of x.
2.Find the point at which the line should begin to angle in order to minimize the total cost.
3. what is the minimum cost?

1 Attachment(s)
You want to find where to put point P so that
$3000 * length of AP + $5000 * length of PB is a minimum.