Jackie and Ken are building a fence around a rectangular field. They want to enclose an area of 75 square feet. The width should be 3 feet longer than the length of the field. What are the dimensions of the field? Round to the nearest tenth, if necessary.

Whiz333
Apr 15, 2017

#1**+1 **

Let the length =L

Then the width =L+3

L x {L+3} =75

Solve for L:

L (L + 3) = 75

Expand out terms of the left hand side:

L^2 + 3 L = 75

Add 9/4 to both sides:

L^2 + 3 L + 9/4 = 309/4

Write the left hand side as a square:

(L + 3/2)^2 = 309/4

Take the square root of both sides:

L + 3/2 = sqrt(309)/2 or L + 3/2 = -sqrt(309)/2

Subtract 3/2 from both sides:

L = sqrt(309)/2 - 3/2 or L + 3/2 = -sqrt(309)/2

Subtract 3/2 from both sides:

Answer: | L = sqrt(309)/2 - 3/2 =~7.3 feet - the length of the field

The width =7.3 + 3 =10.3 feet

Guest Apr 15, 2017