Question

If log47≈1.404
and log45≈1.161
, what is log435
? Use the rule logb(xy)=logbx+logby
to solve.(1 point)
Responses

1.630
1.630

2.565
2.565

0.827
0.827

1.209

1 answer

To find \( \log_4 35 \), we can use the given logarithm values and the property of logarithms \( \log_b(xy) = \log_b(x) + \log_b(y) \).

First, we can express 35 as follows:

\[ 35 = 7 \times 5 \]

Thus, we can write:

\[ \log_4 35 = \log_4 (7 \times 5) = \log_4 7 + \log_4 5 \]

Next, we need to find \( \log_4 5 \). We can express \( \log_4 5 \) using the change of base formula:

\[ \log_4 5 = \frac{\log_4 5^{1}}{1} = \frac{\log_4 5}{\log_4 4} = \frac{\log_4 5}{1} \]

Without directly knowing \( \log_4 5 \), we can also relate it to \( \log_4 7 \). We'll apply the change of base formula:

  1. Expressing \( \log_4 7 \) and \( \log_4 5 \):

    • We have \( \log_4 7 \approx \log 7 / \log 4 \)
    • We have \( \log_4 5 \approx \log 5 / \log 4 \)
  2. Now we can find \( \log_4 7 \) using the provided value of \( \log 7 \):

    • \( \log_4 7 \approx 1.404 \)
    • \( \log_4 5 \approx 1.161 \)

Now substituting the values into the equation:

\[ \log_4 35 \approx \log_4 7 + \log_4 5 = 1.404 + 1.161 \]

Calculating this yields:

\[ \log_4 35 \approx 1.404 + 1.161 \approx 2.565 \]

Therefore, the answer is:

2.565