CurriculumGrade 9Mathematics

Linear vs. Exponential Models

Aligned to F-LE.A.2 — Common Core State Standards for Mathematics.

What this lesson teaches

A linear function adds the same amount each step (a constant difference); an exponential function multiplies by the same factor each step (a constant ratio). Use two points or a table to find the rule.

Worked example

A population doubles yearly, starting at 300. It multiplies by 2 each year, so P(x) = 300 × 2^x. After 3 years, P(3) = 300 × 2^3 = 2400.

Practice questions

  1. Write a linear function through (0, 4) and (1, 9).
  2. A car worth $20,000 loses half its value each year. Write the exponential function.
  3. A table shows 2, 6, 18, 54. Is it linear or exponential? Write its rule.

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Every lesson comes with a video taught in English and Spanish — the same video the QR code in the printed workbook opens.

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En español

Modelos Lineales vs. Exponenciales

Una función lineal suma la misma cantidad en cada paso (una diferencia constante); una función exponencial multiplica por el mismo factor en cada paso (una razón constante). Usa dos puntos o una tabla para hallar la regla.

Ejemplo: Una población se duplica cada año, empezando en 300. Se multiplica por 2 cada año, así que P(x) = 300 × 2^x. Después de 3 años, P(3) = 300 × 2^3 = 2400.

More Functions lessons

Interpreting Graphs of FunctionsF-IF.B.4What Is a Function?F-IF.A.1Evaluating FunctionsF-IF.A.2Sequences as FunctionsF-IF.A.3Domain in ContextF-IF.B.5Average Rate of ChangeF-IF.B.6

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