Please help me understand my math work?

someone please help. I'm trying to understand the example my professor gave me.

f(x)=1/x-3 and I know the solution is domain = (-inf,3) U (3,+inf) and the range is (-inf, 0) U (0, +inf)

Anonymous2012-09-03T18:14:00Z

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Matt2012-09-03T18:12:35Z

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