What are the answer choices for these natural log and composition problems?

In summary, the conversation is about a person struggling with finding the correct answer among multiple choices in their homework. They provide their attempts at solving two problems involving inverse functions and exponential equations, but neither of their answers match the given choices.
  • #1
geegeet
3
0

Homework Statement


I keep getting what I think is the "right answer", but it's not one of my choices :^(
Here are the problems and answer choices.
1).
precal1.jpg

2).
precal2.jpg


Homework Equations



nothing really...or at least I don't think besides the fact that e^-x = 1/e^x

The Attempt at a Solution



1).
x + 14 = 2 g^( - 1) ( x )
(x + 14) / 2 = g^( - 1) ( x)

x - 3 = 4 f^( - 1) ( x)
( x - 3) / 4 = f^( - 1) ( x)

g^( - 1) o f^( - 1) ( x) = (x + 53) / 8
I get this for number 1, but it is not one of the answer choices!

2).
6 = 7e^x + e^(-x )
Let e^x = t, (t > 0), thus e^(-x) = 1/t
6 = 7t + 1/t
Multiplying each side by t
6t = 7t² + 1
7t² - 6t + 1 = 0
t = (3 ± √2)/7
e^x = t ==> x = ln (t)
x = ln [(3 + √2)/7] or x = ln [(3 − √2)/7]
I get this for number 2, but it is also not one of the answer choices!
 
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  • #2
I agree with both your answers.
 

1. What is a natural log?

A natural log, or ln, is a mathematical function that represents the inverse of the exponential function. It is written as ln(x) and is used to find the power to which a constant, e, must be raised to obtain a given number, x.

2. How do natural logs and exponents relate to each other?

Natural logs and exponents are inverse functions of each other. This means that ln(x) and e^x "cancel out" each other, and are used to solve equations involving exponential functions.

3. What is the composition of natural logs?

The composition of natural logs refers to the process of using the ln function on a mathematical expression. For example, ln(e^x) would be written as x, since e^x and ln(x) are inverse functions.

4. How are natural logs used in real-world applications?

Natural logs are commonly used in fields such as economics, biology, and physics to model and analyze exponential growth and decay. They are also used in statistics and probability to analyze data and make predictions.

5. Are there any limitations to using natural logs?

One limitation of using natural logs is that the function is only defined for positive numbers. Additionally, ln(0) is undefined. In some cases, the use of natural logs may also lead to errors when working with very large or very small numbers.

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