Question

Will someone help me work this problem through Please?
I will Medal!

10ln(10r−1)−10=−20

Answer 1

-> 10 ln (10r-1)=-10
-> ln (10r-1)=-1

The rule for log is that

\[q=\log_a(x) \Longleftrightarrow a^q=x.\]

ln means the natural log where a is number e, so

\[e ^{-1}=10r - 1\]

Now put all the knowns to the side of e^(-1) to calculate r

Answer 2

Thank you!