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Ch. 4 - Inverse, Exponential, and Logarithmic Functions
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063당신이 사용하는 게 아니라요?교과서 변경
5장, 문제 29

Solve each equation. logx 25 = -2

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Identify the given equation: \(\log_{x} 25 = -2\).
Recall the definition of logarithm: \(\log_{a} b = c\) means \(a^{c} = b\). Apply this to rewrite the equation as \(x^{-2} = 25\).
Rewrite the equation \(x^{-2} = 25\) as \(\frac{1}{x^{2}} = 25\) to make it easier to solve for \(x\).
Multiply both sides by \(x^{2}\) to get \(1 = 25 x^{2}\), then divide both sides by 25 to isolate \(x^{2}\): \(x^{2} = \frac{1}{25}\).
Take the square root of both sides to solve for \(x\): \(x = \pm \frac{1}{5}\). Remember to check the domain restrictions for the logarithm base.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Definition of Logarithms

A logarithm answers the question: to what exponent must the base be raised to produce a given number? For example, log_b(a) = c means b^c = a. Understanding this definition is essential to rewrite and solve logarithmic equations.
추천 영상:
7:30
Logarithms Introduction

Properties of Logarithms

Logarithmic properties, such as the inverse relationship between logarithms and exponents, help simplify and solve equations. Recognizing that log_b(x) = y implies b^y = x allows conversion between logarithmic and exponential forms.
추천 영상:
5:36
Change of Base Property

Solving Logarithmic Equations

To solve equations like log_x(25) = -2, rewrite the equation in exponential form (x^-2 = 25) and solve for the variable. This process often involves algebraic manipulation and understanding domain restrictions for logarithms.
추천 영상:
5:02
Solving Logarithmic Equations