Evaluate the expression [tex]\log _5 \frac{1}{25}[/tex].

A. [tex]-\frac{1}{2}[/tex]
B. [tex]-2[/tex]
C. [tex]\frac{1}{2}[/tex]
D. [tex]2[/tex]



Answer :

To evaluate the expression [tex]\(\log_5 \frac{1}{25}\)[/tex], follow these steps:

1. Understand the expression:
The expression [tex]\(\log_5 \frac{1}{25}\)[/tex] is asking for the power to which the base 5 must be raised to result in [tex]\(\frac{1}{25}\)[/tex].

2. Express [tex]\(\frac{1}{25}\)[/tex] in terms of base 5:
We know that [tex]\(25\)[/tex] can be written as [tex]\(5^2\)[/tex]. Therefore:
[tex]\[ \frac{1}{25} = \frac{1}{5^2} = 5^{-2} \][/tex]

3. Rewrite the logarithm:
Using the above expression, we can rewrite [tex]\(\log_5 \frac{1}{25}\)[/tex] as [tex]\(\log_5 5^{-2}\)[/tex].

4. Use the logarithm power rule:
The logarithm power rule states that [tex]\(\log_b (a^c) = c \cdot \log_b a\)[/tex]. In this case:
[tex]\[ \log_5 5^{-2} = -2 \cdot \log_5 5 \][/tex]

5. Evaluate the logarithm of the same base:
The property of logarithms [tex]\(\log_b b = 1\)[/tex] gives us:
[tex]\[ \log_5 5 = 1 \][/tex]
So,
[tex]\[ -2 \cdot \log_5 5 = -2 \cdot 1 = -2 \][/tex]

Thus, the value of [tex]\(\log_5 \frac{1}{25}\)[/tex] is [tex]\(-2\)[/tex].

The correct answer is [tex]\(-2\)[/tex].