
1²-2²+3²-4²+5²-6²......-100²+101²怎么做
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1²-2²+3²-4²+5²-6²......-100²+101²
=(1+2)(1-2)+(3+4)(3-4)......(99+100)(99-100)+101²
=-3-7......-199+101²
=-(1+2+3+4+5......)+10201
=-½100(100+1)+10201
=-5050+10201
=5151
=(1+2)(1-2)+(3+4)(3-4)......(99+100)(99-100)+101²
=-3-7......-199+101²
=-(1+2+3+4+5......)+10201
=-½100(100+1)+10201
=-5050+10201
=5151
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