Is (f∘g)(x)(f \circ g)(x)(f∘g)(x) defined if f(x)=1/xf(x) = 1/xf(x)=1/x, g(x)=1/xg(x) = 1/xg(x)=1/x on (0,∞)(0,\infty)(0,∞)?
Yes, always defined
No, at x=0x=0x=0
No, at x=1x=1x=1
When g(x)≠0g(x) \ne 0g(x)=0