单选题
The sum of the first 100 positive integers is 5,050. What is the sum of the first 200 positive integers?
【正确答案】
E
【答案解析】The sum of the first n positive integers is given by 
, so the sum of the first 200 positive integers is
=20,100.Alternatively, letting
represent the sum of the first 100 positive integers, it is given that 
= 5,050. Using this notation, 
, so the sum of the first 200 positive integers is=20,100.Alternatively, letting represent the sum of the first 100 positive integers, it is given that = 5,050. Using this notation,