SOLUTION: I'm having trouble with this word problem, please help :) The length of a certain lot is 20 feet less than four times its width. The area is 4200 sq. ft. What are the dimensions

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: I'm having trouble with this word problem, please help :) The length of a certain lot is 20 feet less than four times its width. The area is 4200 sq. ft. What are the dimensions      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 487863: I'm having trouble with this word problem, please help :)
The length of a certain lot is 20 feet less than four times its width. The area is 4200 sq. ft. What are the dimensions of the lot?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The length of a certain lot is 20 feet less than four times its width. The area is 4200 sq. ft. What are the dimensions of the lot?
---
Let the width be W.
Then the length is 4W-20
----
Equation:
Area = length*width
----
W(4W-20) = 4200
4W^2 - 20W - 4200 = 0
---
W^2 - 5W - 1050 = 0
---
Factor:
W = [5 +- sqrt(25 - 4*-1050)]/2
---
W = [5 +- sqrt(4225)]/2
W = [5 +- 65]/2
--------
Positive solution:
W = 35 (width)
Length = 4*35-20 = 120
==============
Cheers,
Stan H.
===============