SOLUTION: The perimeter of a rectangle is 800m and the are is 80m square .find the length of the rectangle

Algebra.Com
Question 1105757: The perimeter of a rectangle is 800m and the are is 80m square .find the length of the rectangle
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
The perimeter of a rectangle is 800m and the are is 80m square .find the length of the rectangle
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2L + 2W = 800
L + w = 400 --> L = 400 - W
L*W = 80
Sub for L
W*(400-W) = 80
w^2 - 400W + 80 = 0
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation (in our case ) has the following solutons:



For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=159680 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 399.799899899875, 0.200100100125184. Here's your graph:

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W is one of the solutions, L is the other.
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