[問題]考古題Form19 sec8 DS-Q24

[凱薩琳]

Let S be the set of all integers from r to t onclusive. If S1 is the sum of all even integers in S, and S0 is the sum of all odd integers in S, what is the value of S1-S0?

(1)r is odd and t-r=5
(2)r=7

Ans:A

[scujean]

[解]s:{r…t}
s1=偶整數和 s0=基整數和
由1：
假設r=1,t=6 則s:{r…t}={1 2 3 4 5 6} 可得到s0和s1 就算假設r=3或其他奇數 結果也會一樣 你可以試算

[凱薩琳]

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