Building a Function
Aligned to F-BF.A.1 — Common Core State Standards for Mathematics.
What this lesson teaches
To model a relationship, identify the starting value and the rate of change, then write output = rate × input + start.
Worked example
A tree is 4 ft tall and grows 2 ft per year. Its height after x years is h(x) = 2x + 4. After 5 years, h(5) = 2(5) + 4 = 14 ft.
Practice questions
- Write a function for a savings account with $100 that gains $25 per week.
- A candle is 20 cm tall and burns 3 cm per hour. Write its height function.
- A taxi charges $4 plus $2 per mile. Write the cost function.
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
Construir una Función
Para modelar una relación, identifica el valor inicial y la tasa de cambio, luego escribe salida = tasa × entrada + inicio.
Ejemplo: Un árbol mide 4 pies y crece 2 pies por año. Su altura después de x años es h(x) = 2x + 4. Después de 5 años, h(5) = 2(5) + 4 = 14 pies.
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