令 x=1x2+2x3+3x4+4x5+5x6+······+99x100
=[1x1+1]+[2x2+2]+[3x3+3]+[4x4+4]+.+[99x99+99]
=1x1+2x2+3x3+4x4+.+99x99+(1+2+3+4+.+99)
=99x(99+1)x(99+2)/6+99x(99+1)/2
=99x50x37+99x50
=99x50x38
=188100
计算1x2+23+34+45+56+······+99100的结果.
2个回答
相关问题
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试求1×2+23+34+45+56+…+99100的结果.
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计算：12.34+23.45+34.56+45.67+56.78+67.89+78.91+89.12+91.23．
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计算：12.34+23.45+34.56+45.67+56.78+67.89+78.91+89.12+91.23．
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1+12++23+34+45+56
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12.34+23.45+34.56+45.67+56.78.67.89+78.91+89.12+91.23=
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[1.2+2.3+3.4+4.5+5.6/12+23+34+45+56]．
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（1+0.23+0.34）×（0.23+0.34+0.56）-（1+0.23+0.34+0.56）×（0.23+0.34
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﹙1+0.23+0.34﹚×﹙0.23+0.34+0.56)-﹙1+0.23+0.34+0.56﹚×﹙0.23+0.34
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77°42’+34°45’=?108°18’-56°-56°23’=?73°22’48”=?
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(1+0.23+0.34)*(0.23+0.34+0.45)-(1+0.23+0.34+0.45)*(0.23+0.34