Why did the invention of penicillin so important in ww1

This map is depicting the 16th century route of what explorer

You are given the first four terms of an arithmetic sequence. why might you use a recursive formula? why might you use an explicit formula? under what conditions might a recursive formula be preferred over the explicit formula? under what conditions might an explicit formula be preferred over the recursive formula? pleasss ! sorry if it's a long question: (

Why did admiral leahy think the use of the atomic bomb on hiroshima and nagasaki was ethically wrong