luckjoe

Please solve the below problem

https://www.flickr.com/photos/124898006@N08/23104854609/in/dateposted-public/

Thank you very much

sunnytsang

First make e^-x be the subject, then take natural log on both sides.

y=10/(1+3e^-x)
1+3e^-x=10/y
e^-x=(10-y)/3y
-x=ln(10-y)-ln(3y)
x=ln(y)+ln(3)-ln(10-y)

f^-1(x)=ln(x)+ln(3)-ln(10-x)