To find the value of \(\log_4(2.1)\) using the change of base formula, we can use the formula:
\[ \log_b(a) = \frac{\log_k(a)}{\log_k(b)} \]
where \(k\) can be any positive number (commonly we use 10 or \(e\)).
Using base 10:
\[ \log_4(2.1) = \frac{\log_{10}(2.1)}{\log_{10}(4)} \]
Calculating each logarithm using a calculator:
- \(\log_{10}(2.1) \approx 0.322\)
- \(\log_{10}(4) \approx 0.602\)
Now we can plug these values into the change of base formula:
\[ \log_4(2.1) \approx \frac{0.322}{0.602} \approx 0.535 \]
Thus, \(\log_4(2.1)\) to the nearest thousandth is approximately 0.535.