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Question

Hi I'm looking at a graph and trying to find the interval on which f is increasing/decreasing/constant. There are open and closed circles for certain points on the graph. When listing the intervals, do i still use brackets and parenthesis since there are some open circles?

Answer 1

If the circles are open, use parentheses ( or ).  If the circles are closed or solid, use brackets [ or ].

if you begin or end with infinity, the graph continues forever, a parenthesis is always used with infinity.