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Question 155376: 1. A rectangular garden has dimensions of 18 feet by 13 feet. A gravel path of uniform width is to be built around the garden. How wide can the path be if there is enough gravel for 516 square feet? : 1. A rectangular garden has dimensions of 18 feet by 13 feet. A gravel path of uniform width is to be built around the garden. How wide can the path be if there is enough gravel for 516 square feet?
Answer by jim_thompson5910(9162) About Me  (Show Source):
You can put this solution on YOUR website!
# 1

Let x = width of path

First let's find the area of the garden only: Area of Garden = 18*13=234

So the area of the garden only is 234 square feet.

Now let's draw a picture:

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From the picture, notice that the length of the entire rectangle (including the width of the path) is 18+2x (notice there are two "x" lengths per side) and the total width is 13+2x .


So the area of the entire enclosure (including the path) is the expression (18+2x)(13+2x)


(18+2x)(13+2x)-234 Now subtract off the area of the garden (we only want the area of the path)


234+36x+26x+4x^2-234 FOIL


4x^2+62x Combine like terms


So the area of the path only is A=4x^2+62x


A=4x^2+62x Start with the area of the path


516=4x^2+62x Plug in A=516 (which is the area of the path)


0=4x^2+62x-516 Subtract 516 from both sides


Notice we have a quadratic equation in the form of ax^2+bx+c where a=4, b=62, and c=-516


Let's use the quadratic formula to solve for x


x = (-b +- sqrt( b^2-4ac ))/(2a) Start with the quadratic formula


x = (-(62) +- sqrt( (62)^2-4(4)(-516) ))/(2(4)) Plug in a=4, b=62, and c=-516


x = (-62 +- sqrt( 3844-4(4)(-516) ))/(2(4)) Square 62 to get 3844.


x = (-62 +- sqrt( 3844--8256 ))/(2(4)) Multiply 4(4)(-516) to get -8256


x = (-62 +- sqrt( 3844+8256 ))/(2(4)) Rewrite sqrt(3844--8256) as sqrt(3844+8256)


x = (-62 +- sqrt( 12100 ))/(2(4)) Add 3844 to 8256 to get 12100


x = (-62 +- sqrt( 12100 ))/(8) Multiply 2 and 4 to get 8.


x = (-62 +- 110)/(8) Take the square root of 12100 to get 110.


x = (-62 + 110)/(8) or x = (-62 - 110)/(8) Break up the expression.


x = (48)/(8) or x =  (-172)/(8) Combine like terms.


x = 6 or x = -43/2 Simplify.


So the answers are x = 6 or x = -43/2

Since a negative width doesn't make sense, this means that the only solution is x=6


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Answer:

So the width of the path can be up to 6 feet (ie 6 feet is the maximum width)