Question

A rectangular garden is 80 m by 60 m. Part of the garden is torn up to install a strip of lawn of equal width around the garden. The new area of the garden is 800 m squared. How wide is the strip of lawn?

Answer 1

Explanation:

let x < 30 be the width of strip of lawn.

then (80-2x)(60-2x)=800

4800-160x-120x+4x²=800

4x²-280x+4000=0

x²-70 x+1000=0

x²-20x-50x+1000=0

x(x-20)-50(x-20)=0

(x-20)(x-50)=0

x=20,50

x=50(rejected)

x=20 m