The enlarged flower bed is a rectangle and its area is x^2+9x+14 m²
So before its enlargement by 14 m², the area of the rectangle = x^2+9x
As you know, the area of rectangle is equal length times width
so area = x^2+9x
factors:
x^2+9x = x (x + 9)
So the dimensions are x and (x + 9)
Hope it helps.