We are given sides of the rectangle AB = (2x+1) and
AD = 4x.
Area of rectangle = Length × Width
Area = 4x(2x+1).
Distributing 4x over (2x+1), we get
[tex]4x(2x+1) = 4x \times 2x + 4x \times 1[/tex]
[tex]4x \times 2x = 8x^2[/tex] and
[tex]4x \times 1= 4x[/tex]
[tex]4x(2x+1) = 8x^2 + 4x.[/tex]
Therefore, Area = [tex]8x^2 + 4x[/tex].