For any positive integer n, the sum of the first n positive integers euqals [n(n+1)]/2.
What is the sum of all the even integers between 99 and 301?
A. 10100 B 20200 C 22650 D. 40200 E. 45150
答案是搞出来了,B
但是非常费时,并不是把那个公式代进去就行的
不知哪位NN可以帮助一下
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