SOLUTION: The width of a rectangle is 4 cm less than its length. If the area of the rectangle is 87cm^2 what are the dimensions of the rectangle? Round to the nearest thousandth. I have

Algebra.Com
Question 338556: The width of a rectangle is 4 cm less than its length. If the area of the rectangle is 87cm^2 what are the dimensions of the rectangle? Round to the nearest thousandth.
I have figured out the answer as
Length = 11.539
Width = 7.539
Just don't know the formula or how to solve, help would be greatly appreciated thank you.
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
The width of a rectangle is 4 cm less than its length. If the area of the rectangle is 87cm^2 what are the dimensions of the rectangle? Round to the nearest thousandth.
I have figured out the answer as
Length = 11.539
Width = 7.539
--------------------
Area = L*W
L = W+4
Area = (W+4)*W = 87
W^2 + 4W = 87
W^2 + 4W - 87 = 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=364 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 7.53939201416946, -11.5393920141695. Here's your graph:

----------------
W = x (ignore the negative solution)
W = 7.53939 ...
L = 11.53939...
RELATED QUESTIONS

the length of a rectangle is 2 centimeters less than its width. What are the dimensions... (answered by Alan3354)
The width of a rectangle is 4 cm less than half its length. If the perimeter of the... (answered by josgarithmetic)
The length of a rectangle is 2 cm longer than its width. If the diagonal of the rectangle (answered by jorel1380)
The length of a rectangle is 4cm less than thrice its width. If the area is 160 sq cm ,... (answered by ikleyn)
The length of a rectangle is 9 cm less than twice its width. If the area of the rectangle (answered by ewatrrr)
the width of a rectangle is 8 cm. less than its length and the area is 20 sq cm. what are (answered by Fombitz)
if the length of a rectangle is 4 cm longer than its width. The perimeter of the... (answered by josgarithmetic)
The length of a rectangle is 2 centimeters less than twice its width. The perimeter of... (answered by EMStelley,CharlesG2)
The length of a rectangle is 2 centimeters less than twice its width. The perimeter of... (answered by rfer)