SOLUTION: "The length of a rectangular patio is 8 feet less than twice it's width. The area of the patio is 280 square feet. Find the dimensions of the patio." I know for this problem tha

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: "The length of a rectangular patio is 8 feet less than twice it's width. The area of the patio is 280 square feet. Find the dimensions of the patio." I know for this problem tha      Log On


   



Question 962358: "The length of a rectangular patio is 8 feet less than twice it's width. The area of the patio is 280 square feet. Find the dimensions of the patio."
I know for this problem that:
l=2w-8
w=w
However when I try to put the equation together, it doesn't work out at the end. Thanks for the help

Found 2 solutions by stanbon, MathLover1:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
"The length of a rectangular patio is 8 feet less than twice it's width. The area of the patio is 280 square feet. Find the dimensions of the patio."
I know for this problem that:
length =2w-8
width =w
----
Equation:
length*width = Area
(2w-8)w = 280
2w^2-8w-280 = 0
---
w^2 -4w - 140 = 0
----
(w-14)(w+10) = 0
----
Positive solution::
width = 14 ft
length = 2w-8 = 28-8 = 20 ft
-----------------
Cheers,
Stan H.
===========

Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

The length of a rectangular patio is 8ft less than twice it's width.
l=2w-8...eq.1
The area of the patio is A=280ft%5E2.
we know that area is A=l%2Aw
so, l%2Aw=280ft%5E2...now substitute l from eq.1
%282w-8%29%2Aw=280.........solve for w
2w%5E2-8w=280.......both sides divide by 2
w%5E2-4w=140
w%5E2-4w-140=0.......write -4w as 10w-14w
w%5E2%2B10w-14w-140=0......group
%28w%5E2%2B10w%29-%2814w%2B140%29=0
w%28w%2B10%29-14%28w%2B10%29=0
%28w-14%29+%28w%2B10%29+=+0
since we need the width, we can use only positive solution which is

now, go back to eq.1 and calculate l
l=2w-8...eq.1
l=2%2A14-8
l=28-8
highlight%28l=20ft%29
so, the dimensions of the patio are highlight%28l=20ft%29 and highlight%28w=14ft%29