Question

A power station is one side of the river that is one half kilometer wide. A factory is 5 kilometers downstream on the other side of the river. It costs Php 100.00 per meter to run the power lines on the land and Php 150.00 per meter to run underwater. Write the cost C of running the line from the power station to the factory as a function of x.

Answer 1

you don't say what x is
I assume it is the distance (in meters) from the factory to where the pipeline comes ashore. If so, then
C(x) = 100x + 150√((5000-x)^2 + 500^2)