Let f(x)=x2+4 and g(x)=1x-1, then
(2, 3, 4)
dom f=ℝ and dom g={x:x>1}.
Since x2≥0 for any x, so range f=[4,∞) and range g=(0,∞).
Hence, Dom(f+g)=ℝ∩(1,∞)=(1,∞), Range f∩Range g=[4,∞) and Range f∪Range g=(0,∞).