I don't understand what I am doing wrong. I first took the square root of both x^2 and 7 so I got X+7^1/2 then I took the derivative which is just x, after that you take x=3 and plug it in for x which is 3, then you take the opposite reciprocal which is -1/3 which isn't even an answer choice?!?! Can someone please tell me what I am doing wrong?