Properties of Logarithms: Tutorial

Evaluate these logarithms using the properties of logarithms.

[tex]\[
\begin{array}{l}
\log_3 9 + \log_3 27 \\
\log_2 8 - \log_2 4 \\
\log_5 5 (5)^{\frac{1}{3}}
\end{array}
\][/tex]

1. [tex]\log_3 9 + \log_3 27 = [/tex] [tex]\square[/tex]

2. [tex]\log_2 8 - \log_2 4 = [/tex] [tex]\square[/tex]

3. [tex]\log_5 5 (5)^{\frac{1}{3}} = [/tex] [tex]\square[/tex]



Answer :

Sure! Let's work through each of these logarithm problems step-by-step, using the properties of logarithms to simplify the expressions.

### 1. [tex]\(\log_3 9 + \log_3 27\)[/tex]

Using the property of logarithms that states [tex]\(\log_b(m) + \log_b(n) = \log_b(m \cdot n)\)[/tex]:

[tex]\[ \log_3 9 + \log_3 27 = \log_3 (9 \times 27) \][/tex]

Next, we multiply 9 and 27:

[tex]\[ 9 \times 27 = 243 \][/tex]

So,

[tex]\[ \log_3 9 + \log_3 27 = \log_3 243 = \boxed{5} \][/tex]

### 2. [tex]\(\log_2 8 - \log_2 4\)[/tex]

Using the property of logarithms that states [tex]\(\log_b(m) - \log_b(n) = \log_b \left(\frac{m}{n}\right)\)[/tex]:

[tex]\[ \log_2 8 - \log_2 4 = \log_2 \left(\frac{8}{4}\right) \][/tex]

Next, we divide 8 by 4:

[tex]\[ \frac{8}{4} = 2 \][/tex]

So,

[tex]\[ \log_2 8 - \log_2 4 = \log_2 2 = \boxed{1} \][/tex]

### 3. [tex]\(\log_5 5 (5^{\frac{1}{3}})\)[/tex]

Using the property of logarithms that states [tex]\(\log_b(m \cdot n) = \log_b m + \log_b n\)[/tex]:

[tex]\[ \log_5 5 + \log_5 (5^{\frac{1}{3}}) \][/tex]

First, recall that [tex]\(\log_b b = 1\)[/tex], so:

[tex]\[ \log_5 5 = 1 \][/tex]

Next, use the property of logarithms that states [tex]\(\log_b (a^c) = c \cdot \log_b a\)[/tex]:

[tex]\[ \log_5 (5^{\frac{1}{3}}) = \frac{1}{3} \log_5 5 \][/tex]

Since [tex]\(\log_5 5 = 1\)[/tex]:

[tex]\[ \log_5 (5^{\frac{1}{3}}) = \frac{1}{3} \cdot 1 = \frac{1}{3} \][/tex]

Putting it all together:

[tex]\[ \log_5 5 + \log_5 (5^{\frac{1}{3}}) = 1 + \frac{1}{3} = \boxed{1.3333} \][/tex]

So, the final evaluations are:
1. [tex]\(\log_3 9 + \log_3 27 = 5\)[/tex]
2. [tex]\(\log_2 8 - \log_2 4 = 1\)[/tex]
3. [tex]\(\log_5 5 (5^{\frac{1}{3}}) = 1.3333\)[/tex]