Answer:
The rug should be 15 ft wide and 28 ft long.
Step-by-step explanation:
I have attached a figure that represents the situation.
The the rug is
by
, the width of the strip of floor is
.
We are told that Cynthia can only afford 420 square feet of carpeting; therefore, it must be that
<em>(this says the area of the rug must be 420 square feet)</em>
From the figure we see that
![l= 32-2w](https://tex.z-dn.net/?f=l%3D%2032-2w)
![h=19-2w](https://tex.z-dn.net/?f=h%3D19-2w)
Therefore,
![l*h=420\\\\(32-2w)(19-2w)=420](https://tex.z-dn.net/?f=l%2Ah%3D420%5C%5C%5C%5C%2832-2w%29%2819-2w%29%3D420)
We expand this equation and get:
![4w^2-102w+608=420\\\\4w^2-102w+188=0](https://tex.z-dn.net/?f=4w%5E2-102w%2B608%3D420%5C%5C%5C%5C4w%5E2-102w%2B188%3D0)
using the quadratic equation we get two solutions:
![w=2\\w=23.5](https://tex.z-dn.net/?f=w%3D2%5C%5Cw%3D23.5)
since the second solution, namely
, is larger than one of the dimensions of the room (is greater than 19 ft) it cannot be the width of the strip; therefore, we take
to be our solution.
Now we find the dimensions of the rug:
![l=32-2(2)=28\\\\h=19-2(2)=15](https://tex.z-dn.net/?f=l%3D32-2%282%29%3D28%5C%5C%5C%5Ch%3D19-2%282%29%3D15)
The rug is 15 ft wide and 28 ft long.