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Ch. 4 - Inverse, Exponential, and Logarithmic Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 5, Problem 98b

Use the various properties of exponential and logarithmic functions to evaluate the expressions in parts (a)–(c). Given ƒ(x) = log2 x, find ƒ(2log_2 2)

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Identify the given function and the expression to evaluate: ƒ(x) = log_2 x, and we need to find ƒ(2^{log_2 2}).
Recall that ƒ(x) = log_2 x means the logarithm is base 2, so ƒ(2^{log_2 2}) = log_2 (2^{log_2 2}).
Use the logarithmic property that \( \log_b (b^k) = k \) to simplify the expression inside the logarithm.
Apply this property: \( \log_2 (2^{log_2 2}) = log_2 2 \), because the logarithm and the exponent base are the same.
Evaluate \( log_2 2 \) by recognizing that 2 is the base of the logarithm, so \( log_2 2 = 1 \).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Logarithmic Functions

A logarithmic function is the inverse of an exponential function. For a base b > 0 and b ≠ 1, log_b(x) answers the question: to what power must b be raised to get x? Understanding how to evaluate and manipulate logarithms is essential for solving expressions involving log functions.
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Graphs of Logarithmic Functions

Exponential Functions

An exponential function has the form b^x, where the base b is a positive constant not equal to 1. These functions grow or decay rapidly and are the inverse operations of logarithms. Recognizing how to simplify expressions like 2^(log_2 2) relies on understanding this inverse relationship.
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Inverse Properties of Logarithms and Exponentials

Logarithmic and exponential functions with the same base are inverses, meaning log_b(b^x) = x and b^(log_b x) = x. This property allows simplification of nested expressions, such as f(2^(log_2 2)), by 'canceling' the log and exponential when bases match.
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Logarithms Introduction