The range of function y = (tan-1) / (TaNx + 1) is

The range of function y = (tan-1) / (TaNx + 1) is

Let TaNx = t (t ∈ R)
y=(t-1)/(t+1)=(t+1-2)/(t+1)=1-[2/(t+1)]≠1
So the range is {y | y ≠ 1}