/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 4 Write each of the following func... [FREE SOLUTION] | 91Ó°ÊÓ

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Write each of the following functions in the form \(f(t)=A e^{k t} .\) a. \(\quad f(t)=5 \cdot 10^{t}\) b. \(\quad f(t)=5 \cdot 10^{-t}\) c. \(\quad f(t)=7 \cdot 2^{t}\) d. \(\quad f(t)=5 \cdot 2^{-t}\) e. \(\quad f(t)=5\left(\frac{1}{2}\right)^{t}\) f. \(\quad f(t)=5\left(\frac{1}{2}\right)^{-t}\)

Short Answer

Expert verified
(a) A = 5, k = \ln(10); (b) A = 5, k = -\ln(10); (c) A = 7, k = \ln(2); (d) A = 5, k = -\ln(2); (e) A = 5, k = -\ln(2); (f) A = 5, k = \ln(2).

Step by step solution

01

Express the Function in Exponential Form (a)

The given function is \( f(t) = 5 \cdot 10^t \). We can express the base 10 exponent as an exponential function using base \( e \):\[ 10^t = e^{t \ln(10)} \]Substitute this into the original function:\[ f(t) = 5 \cdot e^{t \ln(10)} \]
02

Express the Function in Exponential Form (b)

The given function is \( f(t) = 5 \cdot 10^{-t} \). We can express the base 10 exponent as an exponential function using base \( e \):\[ 10^{-t} = e^{-t \ln(10)} \]Substitute this into the original function:\[ f(t) = 5 \cdot e^{-t \ln(10)} \]
03

Express the Function in Exponential Form (c)

The given function is \( f(t) = 7 \cdot 2^t \). We can express the base 2 exponent as an exponential function using base \( e \):\[ 2^t = e^{t \ln(2)} \]Substitute this into the original function:\[ f(t) = 7 \cdot e^{t \ln(2)} \]
04

Express the Function in Exponential Form (d)

The given function is \( f(t) = 5 \cdot 2^{-t} \). We can express the base 2 exponent as an exponential function using base \( e \):\[ 2^{-t} = e^{-t \ln(2)} \]Substitute this into the original function:\[ f(t) = 5 \cdot e^{-t \ln(2)} \]
05

Express the Function in Exponential Form (e)

The given function is \( f(t) = 5 \left( \frac{1}{2} \right)^t \). Recognizing that \( \frac{1}{2} = 2^{-1} \), we rewrite the function:\[ \left( \frac{1}{2} \right)^t = 2^{-t} \]Now, express the base 2 exponent in terms of base \( e \):\[ 2^{-t} = e^{-t \ln(2)} \]Substitute this into the original function:\[ f(t) = 5 \cdot e^{-t \ln(2)} \]
06

Express the Function in Exponential Form (f)

The given function is \( f(t) = 5 \left( \frac{1}{2} \right)^{-t} \). Recognizing that \( \left( \frac{1}{2} \right)^{-t} = 2^t \), express it in terms of the base \( e \):\[ 2^t = e^{t \ln(2)} \]Substitute this into the original function:\[ f(t) = 5 \cdot e^{t \ln(2)} \]

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Base Conversion
Base conversion is the process of changing a number from one base to another. In the context of exponential functions, it often involves converting expressions to base \(e\), commonly known as the natural exponential base. This is essential because many mathematical models in science and engineering utilize the base \(e\) due to its natural properties in calculus. To convert a base-\(b\) exponentiation to base \(e\), we use the formula \(b^t = e^{t \ln(b)}\). Here, \(\ln(b)\) is the natural logarithm of \(b\). So, when you encounter a function such as \(5 \cdot 10^t\), it can be expressed as \(5 \cdot e^{t \ln(10)}\). This conversion simplifies further calculations and assessments when dealing with exponential growth or decay models.
Natural Logarithm
The natural logarithm, denoted as \(\ln(x)\), is the logarithm to the base \(e\), where \(e\) is approximately 2.71828. It is a critical concept in mathematics due to its relationship with exponential functions and calculus. When you take the natural logarithm of a number, you're essentially asking "To what power must \(e\) be raised to get \(x\)?" For example, in converting a base 2 exponent to base \(e\), we utilize \(\ln(2)\). If you have \(2^t\), and you want it in the form \(e\), you calculate \(e^{t \ln(2)}\). By using the natural logarithm, we can linearize exponential growth or decay, making it easier to manipulate algebraically and integrate into broader mathematical models.
Mathematical Modeling
Mathematical modeling involves using mathematical expressions and equations to represent real-world phenomena. Exponential functions are frequently used in modeling natural processes because they can describe growth and decay. Examples include population growth, radioactive decay, and compound interest. The form \(f(t) = A e^{k t}\) is especially powerful because it reflects continuous growth (or decay) compounded over time. In this representation, \(A\) is the initial value or starting point, \(e\) is the base of natural logarithms that reflects continuous processes, and \(k\) is the rate of growth or decay. By transforming other bases into exponential models with base \(e\), mathematicians can more effectively integrate and differentiate them, enhancing the model's application and predictive power.
Function Transformation
Function transformation involves changing a function's formula to produce variations that can still model the same phenomena in different ways. Changing exponential functions between different bases is an example of this concept. This can involve converting a function from one base to another to simplify the process of analyzing the behavior of exponential relationships. In the exercise given, each function is transformed to the form \(f(t) = Ae^{kt}\), to simplify analysis and calculations. You also see this principle in transforming \(\left( \frac{1}{2} \right)^t\) to its equivalent form based on base \(e\), which is\( e^{-t \ln(2)}\). With transformations, it becomes easier to identify and work with properties such as shifts, stretches, and compressions, making it a robust tool in both theoretical and applied mathematics.

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Most popular questions from this chapter

Compute \(P^{\prime}(t)\) for: a. \(P(t)=e^{5 t}\) b. \(P(t)=\ln 5 t\) c. \(P(t)=e^{t \sqrt{t}}\) d. \(\quad P(t)=e^{\sqrt{2 t}}\) e. \(P(t)=\ln (\ln t)\) f. \(P(t)=e^{\ln t}\) g. \(P(t)=1 /\left(1+e^{t}\right)\) h. \(P(t)=1 / \ln t\) i. \(\quad P(t)=1 /\left(1+e^{-t}\right)\) j. \(\quad P(t)=\left(1+e^{t}\right)^{3}\) k. \(P(t)=\left(e^{\sqrt{t}}\right)^{3} \quad\) l. \(\quad P(t)=\ln \sqrt{t}\)

We introduced the power chain rule \(\left[(u(x))^{n}\right]^{\prime}=n(u(x))^{n-1}[u(x)]^{\prime}\) for fractional and negative exponents, \(n\), in Section 4.3 .1 (see Exercises 4.3 .3 and 4.3 .4 ). Use these rules when necessary in the following exercise. Compute \(y^{\prime}(x)\) and \(y^{\prime \prime}(x)\) for a. \(y(x)=x^{2}+e^{x}\) b. \(y(x)=3 x^{2}+2 e^{x}\) c. \(y(x)=\left(1+e^{x}\right)^{2}\) d. \(y(x)=\left(e^{x}\right)^{2}\) e. \(y(x)=e^{2 x}=\left(e^{x}\right)^{2}\) f. \(y(x)=e^{-x} \quad=\left(e^{x}\right)^{-1}\) g. \(y(x)=e^{3 x} \quad=\left(e^{x}\right)^{3}\) h. \(y(x)=e^{x} \times e^{2 x}\) i. \(y(x)=\left(5+e^{x}\right)^{3}\) j. \(y(x)=\frac{1}{1+e^{x}} \quad=\left(1+e^{x}\right)^{-1}\) k. \(y(x)=\sqrt{e^{x}} \quad=\left(e^{x}\right)^{\frac{1}{2}}\) l. \(y(x)=e^{\frac{1}{2} x}\) m. \(y(x)=e^{0.6 x}=\left(e^{x}\right)^{0.6}\) n. \(y(x)=e^{-0.005 x}\)

Let \(y(x)=e^{x}\). Compute \(y^{\prime}(x), y^{\prime \prime}(x)=\left(y^{\prime}\right)^{\prime},\) and \(y^{\prime \prime \prime}(x)\).

An egg is covered by a hen and is at \(37^{\circ} \mathrm{C}\). The hen leaves the nest and the egg is exposed to \(17^{\circ} \mathrm{C}\) air. a. Draw a graph representative of the temperature of the egg \(t\) minutes after the hen leaves the nest. Mathematical Model 5.5.6 Egg cooling. During any short time interval while the egg is uncovered, the change in egg temperature is proportional to the length of the time interval and proportional to the difference between the egg temperature and the air temperature. b. Let \(T(t)\) denote the egg temperature \(t\) minutes after the hen leaves the nest. Consider a short time interval, \([t, t+\Delta t],\) and write an equation for the change in temperature of the egg during the time interval \([t, t+\Delta t]\). c. Argue that as \(\Delta t\) approaches zero, the terms of your previous equation get close to the terms of $$T^{\prime}(t)=-k(T(t)-17)$$ d. Assume \(\mathrm{T}(0)=37\) and find an equation for \(T(t)\). e. Suppose it is known that eight minutes after the hen leaves the nest the egg temperature is \(35^{\circ} \mathrm{C}\). What is \(k ?\) f. Based on that value of \(k,\) if the coldest temperature the embryo can tolerate is \(32^{\circ} \mathrm{C},\) when must the hen return to the nest?

Use one rule for each step and identify the rule to differentiate a. \(P(t)=3 \ln t+e^{3 t}\) b. \(P(t)=t^{2}+\ln 2 t\) c. \(P(t)=\ln 5\) d. \(P(t)=\ln \left(e^{2 t}\right)\) e. \(P(t)=\ln \left(t^{2}+t\right)\) f. \(P(t)=e^{t^{2}-t}\) g. \(P(t)=e^{1 / x}\) h. \(P(t)=e^{\sqrt{x}}\) i. \(P(t)=\ln \left((t+1)^{2}\right)\) j. \(P(t)=e^{-t^{2} / 2}\)

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