An island is 3 mi from the nearest point on a straight shoreline; that point is 7 mi from a power station Write an equation for the total cost, C, as a function of x, where x is the distance from the (see figure). A Utility company plans to lay electrical cable underwater from the island to the shore shoreline closest to the island and the point where the cable leaves the shore. and then underground along the shore to the power station. Assume that is costs $2600/mi to lay cable underwater and $1300/mi to lay underground cable. At what point should the underwater cable C =0 meet the shore to minimize the cost of the project? (Type an expression.) Island The interval of interest of the objective function is. Cable (Simplify your answer. Type your answer in interval notation.) 3 mi Power The cost is minimized when x is mi. Station (Type an exact answer.) 7 mi The minimum installation cost is $. (Round to the nearest cent as needed.)