第二題可見每個分子既結果同分母中間既數相除,分子得4
(32-12)/(1*2*3)=4/(1*3)=2/1-2/3
(42-22)/(2*3*4)=4/(2*4)=2/2-2/4
...
(1022-1002)/(100*101*102)=4/(100*102)=2/100-2/102
所以原式=(2/1-2/3)+(2/2-2/4)+(2/3-2/5)+(2/4-2/6)+...+(2/100-2/102)
=2/1+2/2-2/101-2/102=15250/5151 我終於明la:P
你地好勁,點練返黎= =:L:L
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