I managed to do all of my homework except this one: How do you solve the equation: ln x - ln 5= -1??
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$\displaystyle \begin{gathered} \ln x - \ln 5 = - 1 \hfill \\ \ln \frac{x} {5} = - 1 \hfill \\ \Leftrightarrow \frac{x} {5} = e^{ - 1} \hfill \\ \Leftrightarrow x = 5e^{ - 1} \hfill \\ \end{gathered} $
how did you do that? You divide the numbers x and 5 together? And after that I just find out what e^-1 is?
Originally Posted by topaz192 how did you do that? You divide the numbers x and 5 together? it is a rule $\displaystyle \log_a x - \log_a y = \log_a \frac xy$ And after that I just find out what e^-1 is? no. leave it as e^{-1}. or you can write the answer as 5/e if you wish
ok i thought e cant get left in the answer?
Originally Posted by topaz192 ok i thought e cant get left in the answer? it can...unless the problem specifically asked you for your answer in decimal
yea it did. so how do you get an answer? isnt e^-1?
Originally Posted by topaz192 yea it did. so how do you get an answer? isnt e^-1? um, just plug it into your calculator
ok! thanks for your time! = )
Originally Posted by topaz192 ok! thanks for your time! = ) you're welcome
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