Query about monopolistic firm

[sumrarubab]

Can a monopolistic firm earn unlimited profit by increasing price?

[Abhitesh]

Typically no.
But consider a case where price elasticity e < -1 i.e. x% increase in price leads to <x% decrease in demand. In this case revenue will become infinite if price keeps increasing. And if cost is also zero then profit becomes infinite.

Try example. elasticity e = (dy/y).(p/dp) = -1/p. Take cost = 0 first and then some finite cost.