Question

An offshore oil well is 1 mile off the coast. The refinery is 2 miles down the coast. If laying pipe in the ocean is twice as expensive as on land, what path should the pipe follow in order to minimize the cost?

** If I have the equations y^2 = 1^2 + x^2 andC(x) 2*sqrt(1+x^2) + (2 -X), I need to know which do I set equal to "0" once I have taken the derivative of the 2nd equations .**