If \( \log _{5} 2=x \) then find \( \log _{25} 800= \)
Step-by-step Solution:
We are given that:
\[
\log_5 2 = x
\]
We need to find:
\[
\log_{25} 800
\]
Step 1: Express in Terms of Base 5
We rewrite the base 25 logarithm using:
\[
\log_{25} a = \frac{\log_5 a}{\log_5 25}
\]
Since \( 25 = 5^2 \), we know:
\[
\log_5 25 = 2
\]
Thus,
\[
\log_{25} 800 = \frac{\log_5 800}{2}
\]
Step 2: Express \( \log_5 800 \)
Factorize 800:
\[
800 = 2^5 \times 5^2
\]
Taking log base 5:
\[
\log_5 800 = \log_5 (2^5 \times 5^2)
\]
Using logarithm properties:
\[
\log_5 800 = 5 \log_5 2 + \log_5 5^2
\]
\[
= 5x + 2
\]
Step 3: Compute \( \log_{25} 800 \)
\[
\log_{25} 800 = \frac{5x + 2}{2}
\]
\[
= 2.5x + 1
\]