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  • For any positive integer n,the sum of the first n positive integers equals [n(n+1)]/2.What is the sum of all the even in

    For any positive integer n,the sum of the first n positive integers equals [n(n+1)]/2.What is the sum of all the even integers between 99 and 301?
    A.\x0510,100
    B.\x0520,200
    C.\x0522,650
    D.\x0540,200
    E.\x0545,150
    C.\x0522,650
    數(shù)學(xué)人氣:846 ℃時(shí)間:2020-05-06 10:52:00
    優(yōu)質(zhì)解答
    求翻譯!
    1~99的和為99*(99+1)/2=4950
    1~301的和為301*(301+1)/2=45451
    100~301的和為45451-4950=40501
    100~301 設(shè)偶數(shù)和為x則奇數(shù)和為x+101 (共202個(gè)數(shù),奇數(shù)和偶數(shù)各101個(gè)奇數(shù)和比偶數(shù)和大101)
    x+(x+101)=40501
    x=20200
    即偶數(shù)和為20200
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