Use the Change of Base Formula to evaluate log877.

Question

mathstudent55 · Answer

Do you mean $ \log_{10} 877$ or $ \log_8 77$ or $\log_{87} 7$, or maybe something else?

mathstudent55 · Answer

$\log_ba = \dfrac{\log_c a}{\log_c b}$

tester97 · Answer

i ment log (base 8)77

mathstudent55 · Answer

Since you have $ \log_8 77$, use the change of base formula above with 
a = 77, b = 8, c = 10

tester97 · Answer

ok i did that and i think i got that wrong cos i got 69.53 =9.62

mathstudent55 · Answer

Using the change of base formula, you should get this.
Now just use a calculator to find the logs of 77 and 8 and divide.

$\log_8 77 = \dfrac{\log_{10} 77}{\log_{10} 8}$

tester97 · Answer

i did that D: and log (base 10)77 is coming up as just 77 on my calculator and log (base 10)8 is coming up as just 8 and then i divide the two i get 9.62.

mathstudent55 · Answer

I don't think you're using your calculator correctly.

With my calculator I get these results

$ \log_{10} 77 = 1.88649$

$ \log_{10} 8 = 0.90309$