怎样求Sn=2+22+222+2...2(n个)?请问:怎样求Sn=2+22+222+2...2(n个)的和?这里先谢过了!
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![怎样求Sn=2+22+222+2...2(n个)?请问:怎样求Sn=2+22+222+2...2(n个)的和?这里先谢过了!](/uploads/image/z/8552838-30-8.jpg?t=%E6%80%8E%E6%A0%B7%E6%B1%82Sn%3D2%2B22%2B222%2B2...2%28n%E4%B8%AA%29%3F%E8%AF%B7%E9%97%AE%3A%E6%80%8E%E6%A0%B7%E6%B1%82Sn%3D2%2B22%2B222%2B2...2%28n%E4%B8%AA%29%E7%9A%84%E5%92%8C%3F%E8%BF%99%E9%87%8C%E5%85%88%E8%B0%A2%E8%BF%87%E4%BA%86%21)
怎样求Sn=2+22+222+2...2(n个)?请问:怎样求Sn=2+22+222+2...2(n个)的和?这里先谢过了!
怎样求Sn=2+22+222+2...2(n个)?
请问:怎样求Sn=2+22+222+2...2(n个)的和?这里先谢过了!
怎样求Sn=2+22+222+2...2(n个)?请问:怎样求Sn=2+22+222+2...2(n个)的和?这里先谢过了!
Sn=n/2(2a +(n-1)d
or
Sn=n/2(a+Tn)
你的last term 是多少?
我来帮你做.
你先给点悬赏分OK?我已经做出来了.
怎样求Sn=2+22+222+2...2(n个)?请问:怎样求Sn=2+22+222+2...2(n个)的和?这里先谢过了!
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