The Bigger weight minus the lower weight
Insert x = 7
so 3/(7+2) - sqr (7-3)
=3 / (9) - sqr (4)
= 1/3 - 2
=1/3 - 6/3
= -5/3
There can be no negative in a sqrt
so x+1 must be equal or greater then 0
x+1

0
x

-1
so all answers must be greater then or equal to -1
-1,0,1,2,3,4,5,6,7,8
(-1,infinity) is the domain