The quadratic has one root with multiplicity 2 if the discriminant is 0, which is

(That is, for a quadratic
, the discriminant is
.)
Set the discriminant equal to 0 and solve for
:





Answer:
√{395×395}=√395²=395 is your answer
The length of the dollhouse room is 156. Because you take the 1248 and divide by the 8. Which then gives you 156. To verify this answer, you would multiply 156 by 8 and you should get the answer 1248. so the length of the room is 156.