Exponential Modeling and Logarithms

Lesson 10

Math

Unit 5

11th Grade

Lesson 10 of 16

Objective


Evaluate common and natural logs using tables, graphs, and calculators.

Common Core Standards


Core Standards

  • F.BF.B.4.C — Read values of an inverse function from a graph or a table, given that the function has an inverse.
  • F.LE.A.4 — For exponential models, express as a logarithm the solution to abct = d where a, c, and d are numbers and the base b is 2, 10, or e; evaluate the logarithm using technology.

Criteria for Success


  1. Describe the common log as the inverse of an exponent with a base of 10.
  2. Describe the natural log as the inverse of an exponent with a base of $$e$$.
  3. Identify key points of common and natural logs using a table of values.
  4. Evaluate common and natural logs without a calculator when possible.
  5. Use a calculator to evaluate common and natural logs and connect these values to tables and graphs.
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Anchor Problems


Problem 1

Given: $${f(x)=e^x}$$ and $${g(x)=10^x}$$

Use your calculator to write a table of values for $${f^{-1}(x)}$$ and $${g^{-1}(x)}$$.

Match the equivalent equations with the tables of values above.

Which graph below represents $${\mathrm{log}_{10}x}$$ and which represents $${\mathrm{log}_ex}$$?

Guiding Questions

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Problem 2

The “Common Log” is a log with a base of $${10}$$. This is written as $${\mathrm{log}(x)}$$.
The “Natural Log” is a log with a base of $$e$$. This is written as $${\mathrm{ln}(x)}$$.

Write each of the following exponential equations as either a common log or the natural log. 

$${10}^x=y$$

$$e^x=y$$

Guiding Questions

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Target Task


Joseph evaluated $${\mathrm{log}_232}$$ in his calculator and got $${1.505}$$. Why does his answer not make sense? How did he “plug in” the value in the calculator? 

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Lesson 9

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Lesson 11

Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Modeling with and Interpreting Exponential Functions

Topic B: Definition and Meaning of Logarithms

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