Solve by completing the square: A rectangular patio has a length of x + 6 m, a width of x + 8 m, and a total area of 400 m^2. Find the dimensions to the nearest tenth.
(x+6)(x+8) = 400
x^2 + 14x + 48 = 400
x^2+14x+49 = 401
(x+7)^2 = 401
x+7 = ±√401
x = -7±√401
or, note that (x+6)(x+8) = ((x+7)-1)((x+7)+1) = (x+7)^2 - 1
and then the last three lines are the same.