Math Help - Application of the MVT?

1. Application of the MVT?

Show that the equation $ln(1+e^x) = cos(x)$ has infinitely many negative solutions. Is there a positive solution? Is it unique?

2. Originally Posted by DaRush19
Show that the equation $ln(1+e^x) = cos(x)$ has infinitely many negative solutions. Is there a positive solution? Is it unique?
Have you looked at the graph of the two functions? That will tell you a lot.
Note that $x<0$ implies $0<\ln(1+e^x)<1$.