In a given programming language, an identifier is a sequence of a certain number of characters in which the first character must be a letter of the English alphabet and the rest can be a letter or a digit. a How many identifiers are there of length 5?
b. In particular, some implementations of Pascal and identifier is a sequence of 1 to 8 characters with the above description. How many Pascal identifiers are there? I tried to do this: there are five spaces, the first is 26 and the others could be 36 because 10+26, but I don’t know how to resolve this. I don’t know how to resolve b.
Well, there are $26$ possibilities for the first character, and $26+10$ possibilities for the remaining 4 spots. That's: $(26)(36^4)=43,670,016$ possible combinations
As for $n$ characters, there will be $(26)(36^{n-1})$ possible combinations