Ok this is gonna sound weird but i got 4 answers for that, one of which was 9, because a square root can be positive or negative. So i had 10 - 1 = 9, 10 - -1 = 11, -10 - 1 = -9, -10 - -1 = -11
I found it weird that they seemed to only ask for one solution, unless there was another parameter to...