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Piecewise and Step Functions

A piecewise function uses different formulas for different parts of its domain: [formula] To evaluate: check which condition x satisfies, then use that fo…

Theory

Piecewise Functions

A piecewise function uses different formulas for different parts of its domain: [formula] To evaluate: check which condition x satisfies, then use that formula. Example: f(-3) = (-3)^2 = 9 (use first piece since -3 < 0) f(4) = 2(4) + 1 = 9 (use second piece since 4 geq 0)

Example: For the function above, find f(0).

Summary

ACT Pro Tip

On piecewise function questions, the most common mistake is using the wrong piece. Always check the inequality conditions carefully — pay attention to < vs leq (open vs closed circle on the graph).

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