Chapter 9.6, Problem 285E

In the following exercises, solve. Round answers to the nearest tenth.

285. A rancher is going to fence three sides of a corral next to a river. He needs to maximize the corral area using 240 feet of fencing. The quadratic equation $A\left(x\right)=x\left(240-2x\right)$ gives the area of the corral, A, for the length, x, of the corral along the river. Find the length of the corral along the river that will give the maximum area, and then find the maximum area of the corral.