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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 7.3.1c

In Exercises 1–4, solve for t.
1. c. e^((ln 0.2)t) = 0.4

Guida verificata passo dopo passo
1
Recognize that the equation is given as \(e^{(\ln 0.2) t} = 0.4\). The goal is to solve for \(t\).
Recall the property of exponents and logarithms: \(e^{\ln a} = a\). This means the expression \(e^{(\ln 0.2) t}\) can be rewritten as \((e^{\ln 0.2})^t = (0.2)^t\).
Rewrite the equation using this property: \((0.2)^t = 0.4\).
To solve for \(t\), take the natural logarithm of both sides: \(\ln((0.2)^t) = \ln(0.4)\).
Use the logarithm power rule to bring down the exponent: \(t \cdot \ln(0.2) = \ln(0.4)\). Then isolate \(t\) by dividing both sides by \(\ln(0.2)\): \(t = \frac{\ln(0.4)}{\ln(0.2)}\).

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Properties of Logarithms and Exponents

Understanding how logarithms and exponents interact is essential, especially that e^(ln a) = a. This allows simplification of expressions like e^((ln 0.2)t) to (0.2)^t, making the equation easier to solve.
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