# College Algebra

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You have 800 feet of fencing to enclose a rectangular plot that borders on a river. If you do not fence the side along the river,find the length and width of the plot that will maximize the area. What is the largest area that can be enclosed?

• College Algebra -

I know how to do this with calculus, but algebraically it starts the same way.

L + 2W = 800 L = 800 - 2w
A = LW

A= (800-2w)w

A = 800w - 2w^2

Take the derivative: 800 -4w
800 -4w = 0 to find max.
800 = 4w
200 =w
l = 400

• College Algebra -

Thank you!

• College Algebra -

How did it become 800-4w from 2400-2w^2?

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