The length of a rectangle is four times its width. if the area of the rectangle is 100 cm2, find its perimeter.

Define x:

Let the width be x.

width = x

Length = 4x

Given the area, find Length and Width:

The area is 100 cm²

Area = Length x Width

x (4x) = 100

Evaluate the Left Hand Side:

4x² = 100

Divide by 4:

x² = 25

Square root both sides:

x = 5

Find the Width and the Length:

Width = x = 5

Length = 4x = 4 (5) = 20

Find Perimeter:

Perimeter = 2 (5 + 20) = 50 m

Answer: Perimeter = 50 m