Homework Help: math

Posted by Jordan on Tuesday, March 20, 2012 at 3:18am.

Find the dimensions of a rectangle with perimeter 40 with the largest area. (hint: Find an equation for area and one for perimeter, use both to find perimeter in terms of one variable)

math - Reiny, Tuesday, March 20, 2012 at 9:06am
let the width be x
and the length be y

2x + 2y = 40 or
x+y=20 ---> y = 20-x

Area = xy = x(20-x
= 20x - x^2

Are you in Calculus?
Then the solution is very easy

If not in Calculus, complete the square of this quadratic, again a very basic problem.

Let me know what you get.

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