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Devonte used the change of base formula to approximate [tex]\log_8 25[/tex]. Which expression did Devonte use?

A. [tex]\log \frac{8}{25}[/tex]
B. [tex]\frac{\log 8}{\log 25}[/tex]
C. [tex]\log \frac{25}{8}[/tex]
D. [tex]\frac{\log 25}{\log 8}[/tex]

Sagot :

To solve for [tex]\(\log_8(25)\)[/tex], Devonte used the Change of Base Formula. The Change of Base Formula is useful when you need to compute logarithms with bases other than 10 or e (the natural logarithm base), which are directly supported by most calculators.

The Change of Base Formula states that for any positive numbers [tex]\(a\)[/tex], [tex]\(b\)[/tex], and [tex]\(c\)[/tex] (where [tex]\(a \neq 1\)[/tex] and [tex]\(b \neq 1\)[/tex]):

[tex]\[ \log_a b = \frac{\log_c b}{\log_c a} \][/tex]

In our specific case, we want to approximate [tex]\(\log_8(25)\)[/tex], so let's apply the formula:

[tex]\[ \log_8(25) = \frac{\log (25)}{\log (8)} \][/tex]

Here, the expression [tex]\(\frac{\log (25)}{\log (8)}\)[/tex] represents the base 8 logarithm of 25 using the common logarithm (base 10).

Thus, Devonte used the following expression to approximate [tex]\(\log_8(25)\)[/tex]:

[tex]\[ \boxed{\frac{\log 25}{\log 8}} \][/tex]

Now, let's verify that this is indeed the correct expression:

Given our earlier calculations, [tex]\(\frac{\log 25}{\log 8} \approx 1.5479520632582415\)[/tex], we can be confident that:

[tex]\[ \log_8(25) \approx 1.5479520632582415 \][/tex]

Therefore, Devonte correctly used the expression:

[tex]\[ \frac{\log 25}{\log 8} \][/tex]

[tex]\[ \boxed{\frac{\log 25}{\log 8}} \][/tex]