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Unit 3

Exponential and Logarithmic Functions

Growth by constant ratio, and the inverse that recovers the exponent. Most of the unit follows from those two sentences.

Lessons and exercises

Lesson 3.1

Exponential Models

An exponential model multiplies by a constant factor over equal input intervals. The initial value is the output at input zero. A growth factor above 1 increases values, while a factor between 0 and 1 models decay. Identify the time unit before interpreting a percentage rate.

Lesson 3.2

Logarithm Properties

A logarithm gives an exponent. Product and quotient rules require positive arguments over the real numbers. Apply the rules to factors, not terms of a sum. The power rule moves an exponent outside a logarithm when the relevant real-domain conditions hold.

Lesson 3.3

Solving and Domains

Use inverse operations to solve exponential and logarithmic equations. A logarithmic equation over the reals requires every original logarithm argument to be positive. Solving a transformed equation can produce candidates outside that domain, so check the original expressions.

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