The condition says (x+5)^2 = 4x^2 where x is the original dimension of the house. x^2 + 10x + 25 = 4x^2 ====> 3x^2 - 10x - 25 = 0 x == . We are looking for the positive root, which is x = 5. Answer. The original size of the square house was 5 meters. The extended size is 10 meters.