Evaluating Functions
Aligned to F-IF.A.2 — Common Core State Standards for Mathematics.
What this lesson teaches
To evaluate f(x) at a value, substitute that value for x and simplify. In context, f(a) = b means the input a produces the output b.
Worked example
If f(x) = 3x − 4, find f(5). Substitute: f(5) = 3(5) − 4 = 15 − 4 = 11.
Practice questions
- If f(x) = 2x + 7, find f(3).
- If g(x) = x^2 − 1, find g(4).
- A cost function is C(n) = 5n for n tickets. Interpret C(6) = 30.
Watch the lesson
Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.
▶ Watch this lessonEn español
Evaluar Funciones
Para evaluar f(x) en un valor, sustituye ese valor por x y simplifica. En el contexto, f(a) = b significa que la entrada a produce la salida b.
Ejemplo: Si f(x) = 3x − 4, halla f(5). Sustituye: f(5) = 3(5) − 4 = 15 − 4 = 11.
More Functions lessons
Interpreting Graphs of FunctionsF-IF.B.4What Is a Function?F-IF.A.1Sequences as FunctionsF-IF.A.3Domain in ContextF-IF.B.5Average Rate of ChangeF-IF.B.6Graphing Key FeaturesF-IF.C.7
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