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Write the rule of the function in the form \(\left.f(x)=a^{x} . \text { (See the discussion and box after Example } 11 .\right)\) $$f(x)=e^{1.6094 x}$$

Short Answer

Expert verified
Question: Rewrite the function \(f(x) = e^{1.6094x}\) in the form of \(f(x) = a^x\). Answer: The function can be rewritten as \(f(x) = (e^{1.6094})^x\).

Step by step solution

01

Identify the Expression We Want to Rewrite

In this case, we want to rewrite the exponential part of our function, which is \(e^{1.6094x}\), by finding a base "a" such that the function becomes \(a^x\).
02

Rewrite the Expression as \(a^{1x}\)

Rewrite the given exponential function as \(a^{1x}\), which means \(a = e^{1.6094}\).
03

Find the Value of "a" using Logarithms

We can use logarithms to find the value of "a" by solving the equation, \(a = e^{1.6094}\). We take the natural logarithm (ln) of both sides: \(\ln(a) = \ln(e^{1.6094})\)
04

Use the Logarithm Property to Bring the Exponent Down

We can use the logarithm property \(\ln(a^b) = b\ln(a)\) to bring the exponent down: \(\ln(a) = 1.6094 * \ln(e)\) Since \(\ln(e) = 1\), \(\ln(a) = 1.6094\)
05

Find "a" using the Inverse of Natural Logarithm

To find the value of "a", we must undo the natural logarithm using the inverse of natural logarithm (exponential function): \(a = e^{\ln(a)}\) \(a = e^{1.6094}\)
06

Rewrite the Original Function with the New Base "a" (Final Answer)

Now that we have found the value of "a" which is \(e^{1.6094}\), we can rewrite the original function: \(f(x) = a^x\) \(f(x) = (e^{1.6094})^x\) Hence, the rule of the function can be written in the form of \(f(x) = a^x\) as: $$f(x) = (e^{1.6094})^x$$

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Key Concepts

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

Logarithms
Logarithms are a fundamental concept in mathematics, especially when dealing with exponential functions. At its core, a logarithm answers the question: "To what power must a base be raised to obtain a certain number?"
For instance, in the equation \(log_b(a) = c\), \(b\) is the base, \(a\) is the result, and \(c\) is the power or exponent. This means that \(b^c = a\).

Logarithms allow us to reverse the process of exponentiation, making them incredibly useful for solving equations involving exponentials. They are the inverse functions of exponential functions.
Important properties of logarithms include:
  • \(log_b(b) = 1\), because any base raised to the power of 1 is itself.
  • \(log_b(1) = 0\), because any base raised to the power of 0 is 1.
  • Product Rule: \(log_b(XY) = \log_b(X) + \log_b(Y)\).
  • Quotient Rule: \(log_b\left(\frac{X}{Y}\right) = \log_b(X) - \log_b(Y)\).
  • Power Rule: \(log_b(X^c) = c \cdot \log_b(X)\).
Natural Logarithm
The natural logarithm is a special type of logarithm, which uses the base \(e\). The number \(e\) is approximately equal to 2.71828 and is an irrational and transcendental number. The natural logarithm of a number \(x\) is written as \(\ln(x)\).
What makes natural logarithms particularly useful is their simplification properties when calculating with the exponential function. Specifically, the natural logarithm is the inverse of the natural exponentiation. This means:
  • \(\ln(e^x) = x\)
  • \(e^{\ln(x)} = x\)

These properties make natural logarithms helpful in calculus and real-world applications like continuously compounded interest in finance. In the context of our exercise, the relationship \(\ln(e) = 1\) is crucial because it simplifies calculations involving the base \(e\).
Remember that natural logarithm operations follow the same rules as regular logarithms but are specifically tailored for the base \(e\).
Exponentiation
Exponentiation is the process of raising a number, known as the base, to a power or exponent. This mathematical operation is denoted as \(a^n\), where \(a\) is the base and \(n\) is the exponent.
Exponentiation is foundational for understanding many mathematical concepts and naturally occurring phenomena, such as exponential growth or decay. Key points include:
  • Any number raised to the power of 1 remains the same: \(a^1 = a\).
  • Any number raised to the power of 0 is 1: \(a^0 = 1\), provided \(a eq 0\).
  • The process of exponentiation involves repeated multiplication when the exponent is a natural number; for example, \(a^3 = a \times a \times a\).

In the context of the solution provided, understanding exponentiation helps us see how functions like \(f(x) = e^{1.6094x}\) operate and evolve. Exponentiation by \(e\) and transformations such as those in the original exercise illustrate the methods by which exponential expressions are manipulated and understood.
Base Change Formula
The base change formula is an essential tool when you want to convert a logarithm from one base to another. This is particularly useful in various mathematical problems, including the one in our original exercise.
The formula is given by:
  • \(\log_b(a) = \frac{\log_c(a)}{\log_c(b)}\)
This equation lets you change the base from \(b\) to any other base \(c\). Typically, we use common logarithms (base 10) or natural logarithms (base \(e\)).
By leveraging this formula, you can compute a logarithm in one base using known logarithms in another base, thus providing flexibility and convenience, especially when dealing with computational tools that might only support certain bases.
Understanding the base change concept is pivotal for solving exercises that require a specific form. In our case, while not directly used, the principle helps us comprehend how we transition from a natural base \(e\) into the desired format, facilitating a broader understanding of exponential functions. This ability to shift perspectives on the base underscores many calculations in algebra and beyond.

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Most popular questions from this chapter

Look back at Section \(4.4,\) where the basic properties of graphs of polynomial functions were discussed. Then review the basic properties of the graph of \(f(x)=a^{x}\) discussed in this section. Using these various properties, give an argument to show that for any fixed positive number \(a(\neq 1),\) it is not possible to find a polynomial function \(g(x)=c_{n} x^{n}+\dots+c_{1} x+c_{0}\) such that \(a^{x}=g(x)\) for \(a l l\) numbers \(x .\) In other words, no exponential function is a polynomial function. However, see Exercise \(81 .\)

Deal with the compound interest formula \(A=P(1+r)^{t},\) which was discussed in Special Topics \(5.2.A\). (a) How long will it take to triple your money if you invest 500 dollars at a rate of \(5 \%\) per year compounded annually? (b) How long will it take at \(5 \%\) compounded quarterly?

(a) Graph \(f(x)=x^{5}\) and explain why this function has an inverse function. (b) Show algebraically that the inverse function is \(g(x)=x^{1 / 5}\) (c) Does \(f(x)=x^{6}\) have an inverse function? Why or why not?

Determine whether an exponential, power, or logarithmic model (or none or several of these) is appropriate for the data by determining which (if any) of the following sets of points are approximately linear: $$\\{(x, \ln y)\\}, \quad\\{(\ln x, \ln y)\\}, \quad\\{(\ln x, y)\\}$$ where the given data set consists of the points \(\\{(x, y)\\}\) $$\begin{array}{|l|c|c|c|c|c|c|} \hline x & 3 & 6 & 9 & 12 & 15 & 18 \\ \hline y & 385 & 74 & 14 & 2.75 & .5 & .1 \\ \hline \end{array}$$

Rationalize the denominator and simplify your answer. $$\frac{2}{\sqrt{6}}$$

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