The function f of x is to be graphed on a coordinate plane. f of x is equal to negative x when x is less than 0; f of x is equal to 1 when x is greater than or equal to 0 At what point should an open circle be drawn?

For x < 0, the rule is f(x) = -x, which approaches 0 as x approaches 0 from the left. Since x = 0 is not included in that rule, draw an open circle at (0, 0). The rule f(x) = 1 includes x = 0, so (0, 1) is closed, not open.

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