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初一数学帮帮忙`,求你们拉2/1×3＝1/1-1/312/3×5=1/3-1/522/5×7=1/5-1/732/7×9=1/7-1/94……（1）猜测：第N个等式为.(2)由(1)的结果,计算1/3+1/15+1/
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(1):2/n(n+2)=n/(2n-1)-1/(2n+1) n
(2):1/3+1/15+1/35+1/63+1/99+1/143
=2(1/3+1/15+1/35+1/63+1/99+1/143)/2
=(2/1×3+2/3×5+2/5×7+2/7×9+2/9×11+1/11×13)/2
=1/1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13
=1/1-1/13
=12/13
(2):1/3+1/15+1/35+1/63+1/99+1/143
=2(1/3+1/15+1/35+1/63+1/99+1/143)/2
=(2/1×3+2/3×5+2/5×7+2/7×9+2/9×11+1/11×13)/2
=1/1-1/3+1/3-1/5+1/5-1/7+1/7-1/9+1/9-1/11+1/11-1/13
=1/1-1/13
=12/13
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