Express each logarithm in terms of [tex]\ln 3[/tex] and [tex]\ln 5[/tex].

[tex]\ln \frac{81}{125}[/tex]

A. [tex]4 \ln 5 - 3 \ln 3[/tex]

B. [tex]5 \ln 3 - 3 \ln 4[/tex]

C. [tex]4 \ln 3 - 3 \ln 5[/tex]

D. [tex]3 \ln 4 - 5 \ln 3[/tex]



Answer :

Let's start by examining each expression one by one, focusing on expressing the logarithms in terms of [tex]\(\ln 3\)[/tex] and [tex]\(\ln 5\)[/tex].

### 1. [tex]\(\ln \frac{81}{125}\)[/tex]

First, let's rewrite 81 and 125 as powers of their prime factors:
- [tex]\(81 = 3^4\)[/tex]
- [tex]\(125 = 5^3\)[/tex]

Thus, the expression becomes:

[tex]\[ \ln \frac{81}{125} = \ln \frac{3^4}{5^3} \][/tex]

Using the property of logarithms [tex]\(\ln \left( \frac{a}{b} \right) = \ln a - \ln b\)[/tex]:

[tex]\[ \ln \frac{3^4}{5^3} = \ln 3^4 - \ln 5^3 \][/tex]

Now, applying the power rule of logarithms, [tex]\(\ln a^b = b \ln a\)[/tex]:

[tex]\[ \ln 3^4 - \ln 5^3 = 4 \ln 3 - 3 \ln 5 \][/tex]

So,

[tex]\[ \ln \frac{81}{125} = 4 \ln 3 - 3 \ln 5 \][/tex]

### 2. [tex]\(4 \ln 5 - 3 \ln 3\)[/tex]

This expression is already expressed in terms of [tex]\(\ln 3\)[/tex] and [tex]\(\ln 5\)[/tex]:

[tex]\[ 4 \ln 5 - 3 \ln 3 \][/tex]

No further manipulation is needed.

### 3. [tex]\(5 \ln 3 - 3 \ln 4\)[/tex]

To express this in terms of [tex]\(\ln 3\)[/tex] and [tex]\(\ln 5\)[/tex], we need to rewrite [tex]\(\ln 4\)[/tex] in terms of these logarithms:

Since [tex]\(4 = 2^2\)[/tex],

[tex]\[ \ln 4 = \ln 2^2 = 2 \ln 2 \][/tex]

If more information about [tex]\(\ln 2\)[/tex] were given, we could substitute it into our expression. However, since we are asked only to use [tex]\(\ln 3\)[/tex] and [tex]\(\ln 5\)[/tex], the expression remains in its current form for now:

[tex]\[ 5 \ln 3 - 3 \cdot 2 \ln 2 = 5 \ln 3 - 6 \ln 2 \][/tex]

### 4. [tex]\(4 \ln 3 - 3 \ln 5\)[/tex]

This expression is already expressed in terms of [tex]\(\ln 3\)[/tex] and [tex]\(\ln 5\)[/tex]:

[tex]\[ 4 \ln 3 - 3 \ln 5 \][/tex]

No further manipulation is needed.

### 5. [tex]\(3 \ln 4 - 5 \ln 3\)[/tex]

Again, expressing [tex]\(\ln 4\)[/tex] in terms of [tex]\(\ln 3\)[/tex] and [tex]\(\ln 5\)[/tex]:

Since [tex]\(4 = 2^2\)[/tex],

[tex]\[ 3 \ln 4 = 3 \ln 2^2 = 3 \cdot 2 \ln 2 = 6 \ln 2 \][/tex]

So, the expression is:

[tex]\[ 6 \ln 2 - 5 \ln 3 \][/tex]

If there were details connecting [tex]\(\ln 2\)[/tex] with [tex]\(\ln 3\)[/tex] or [tex]\(\ln 5\)[/tex], we could substitute those in. Since we lack that information, the expression remains unchanged.

### Summary

The expressions in terms of [tex]\(\ln 3\)[/tex] and [tex]\(\ln 5\)[/tex] are:
1. [tex]\(\ln \frac{81}{125} = 4 \ln 3 - 3 \ln 5\)[/tex]
2. [tex]\(4 \ln 5 - 3 \ln 3\)[/tex]
3. [tex]\(5 \ln 3 - 6 \ln 2\)[/tex]
4. [tex]\(4 \ln 3 - 3 \ln 5\)[/tex]
5. [tex]\(6 \ln 2 - 5 \ln 3\)[/tex]

Expressions 3 and 5 contain [tex]\(\ln 2\)[/tex], which cannot be simplified further without additional information about [tex]\(\ln 2\)[/tex]. The other expressions are already in the desired form.