Logarithms

[Violagirl]

I just took a quiz and my teacher corrected it. I'm not sure what I did wrong on these problems:

log(3)27+log(2)16? My teacher says the answer is 7. How do you get that?

And then this one: log(31)59-log 41.3+ln 29.81-log 74+ln 56-log(19)75? My teacher got 3.6561. How would you do that one?

 

[tkhunny]

\(\displaystyle log_{3}(27) = log_{3}(3^{3}) = 3log_{3}(3) = 3*1 = 3\)

Do the same with the 2-log and you will see it.

 

[skeeter]

And then this one: log(31)59-log 41.3+ln 29.81-log 74+ln 56-log(19)75? My teacher got 3.6561. How would you do that one?

use the change of base formula for logs (for those terms that need changing) ... oh, and a calculator.