1,设等差数列共有2n+1项,所有奇数项的和为132,所有偶数项的和为120,则n等于多少第2题{an}是公差为-2的等差数列,若a1+a4+a7+.+a97=50,那么a3+a6+a9+.+a99等于多少第三题若a,b,c,d,e成等差数列,则(b+a+d)/(a+e)
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![1,设等差数列共有2n+1项,所有奇数项的和为132,所有偶数项的和为120,则n等于多少第2题{an}是公差为-2的等差数列,若a1+a4+a7+.+a97=50,那么a3+a6+a9+.+a99等于多少第三题若a,b,c,d,e成等差数列,则(b+a+d)/(a+e)](/uploads/image/z/8811690-42-0.jpg?t=1%2C%E8%AE%BE%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%E5%85%B1%E6%9C%892n%2B1%E9%A1%B9%2C%E6%89%80%E6%9C%89%E5%A5%87%E6%95%B0%E9%A1%B9%E7%9A%84%E5%92%8C%E4%B8%BA132%2C%E6%89%80%E6%9C%89%E5%81%B6%E6%95%B0%E9%A1%B9%E7%9A%84%E5%92%8C%E4%B8%BA120%2C%E5%88%99n%E7%AD%89%E4%BA%8E%E5%A4%9A%E5%B0%91%E7%AC%AC2%E9%A2%98%7Ban%7D%E6%98%AF%E5%85%AC%E5%B7%AE%E4%B8%BA-2%E7%9A%84%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%2C%E8%8B%A5a1%2Ba4%2Ba7%2B.%2Ba97%3D50%2C%E9%82%A3%E4%B9%88a3%2Ba6%2Ba9%2B.%2Ba99%E7%AD%89%E4%BA%8E%E5%A4%9A%E5%B0%91%E7%AC%AC%E4%B8%89%E9%A2%98%E8%8B%A5a%2Cb%2Cc%2Cd%2Ce%E6%88%90%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%2C%E5%88%99%28b%2Ba%2Bd%29%2F%28a%2Be%29)
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