The value of x for which 11+x,11−x ,11−x are in A.P lie in
(-1,1)
[0,1)∪(1,∞)
(0,∞)
-2,2
For x to be defined we must havex≥0 .
Also for 11−x and 11−x to be defined we must havex≠1.
For x∈[0,1)∪(1,∞) , We have 21−x=11−x+11+x