The dimensions of the bulletin board is 2 ft and 9 ft.
Let the width of board = x
Then, the length of board = 7+x
Area of board = 18 ft²
Area of rectangle = L×W
so, (7+x) × x = 18 ft²
7x + x² = 18 ft²
7x + x² + 18 = 0
x² + 9x -2x -18 = 0
x(x+9) -2(x+9) = 0
(x+9) (x-2) = 0
x+9 =0, x -2 = 0
Dimension can not be in negative number, so
x = 2, Width = 2 ft
Length = 2+7 = 9 ft
Hence, the dimensions of board will be:
The width of board = 2 ft
And, the length of bard = 9 ft.