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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 97

Solve each equation for the indicated variable. Use logarithms with the appropriate bases. A = P (1 + r/n)tn, for t

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Identify the given formula: \(A = P (1 + \frac{r}{n})^{tn}\), where \(A\) is the amount, \(P\) is the principal, \(r\) is the interest rate, \(n\) is the number of times interest is compounded per year, and \(t\) is the time in years. We need to solve for \(t\).
Start by isolating the exponential term. Divide both sides of the equation by \(P\) to get: \(\frac{A}{P} = (1 + \frac{r}{n})^{tn}\).
To solve for \(t\), take the logarithm of both sides. Since the base of the exponent is \(1 + \frac{r}{n}\), use the logarithm with this base: \(\log_{(1 + \frac{r}{n})} \left( \frac{A}{P} \right) = \log_{(1 + \frac{r}{n})} \left( (1 + \frac{r}{n})^{tn} \right)\).
Apply the logarithmic identity \(\log_b (b^x) = x\) to simplify the right side: \(\log_{(1 + \frac{r}{n})} \left( \frac{A}{P} \right) = tn\).
Finally, solve for \(t\) by dividing both sides by \(n\): \(t = \frac{1}{n} \log_{(1 + \frac{r}{n})} \left( \frac{A}{P} \right)\).

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주요 개념

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

Exponential Equations

Exponential equations involve variables in the exponent, such as (1 + r/n)^(tn). Solving for a variable in the exponent requires techniques like logarithms to rewrite the equation in a solvable form.
추천 영상:
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Solving Exponential Equations Using Logs

Logarithms and Their Properties

Logarithms are the inverse operations of exponentials and allow us to solve equations where the variable is an exponent. Understanding properties like log_b(a^c) = c log_b(a) is essential for isolating variables in exponential expressions.
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Change of Base Property

Compound Interest Formula

The formula A = P(1 + r/n)^(tn) calculates compound interest, where A is the amount, P is the principal, r is the interest rate, n is the number of compounding periods per year, and t is time. Recognizing this formula helps identify which variable to solve for.
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Solving Quadratic Equations Using The Quadratic Formula