Word problem of rectangular garden.

Question

amie plans to use part of her back yard to plant a rectangular garden. if the length is to be 21 feet greater than the width and the area of the garden is 100 sq ft, find the dimensions of the garden and find the perimeter of the garden.

Answer 1

The formula for the area of a rectangle is Side x Side.   Since they only give you one side and the answer you need to alter the problem (or use algebra) to figure it out.

 

For example:

 

I would simply divide 100ft2 by 21ft, you'll come up 4.76 ft. If you multiply 4.76 ft x 21 ft you'll have 99.96 ft2 rounding up to 100ft² is reasonable in this case.  If you need to be exact, use the exact answer from 100ft²/21 ft.

Answer 2

w=width

w+21=length

A=lw

100=w(w+21)

100=w²+21w

w²+21w-100=0

(w+25)(w-4)=0

w-4=0

w=4 feet

l=4+21=25 feet