1/3×6+1/6×9+1/9×12+····+1/45×48这题要简便计算一定要在今天回答

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1/3×6+1/6×9+1/9×12+····+1/45×48这题要简便计算一定要在今天回答1/3×6+1/6×9+1/9×12+····+1/45×48这题要简便计算一定要在今天回答1/3×6+1/

1/3×6+1/6×9+1/9×12+····+1/45×48这题要简便计算一定要在今天回答
1/3×6+1/6×9+1/9×12+····+1/45×48
这题要简便计算
一定要在今天回答

1/3×6+1/6×9+1/9×12+····+1/45×48这题要简便计算一定要在今天回答
1/3x6+1/6x9+1/9x12+.+1/45x48
解原式=1/3×(1/3-1/6+1/6-1/9+……+1/45-1/48)
=1/3×(1/3-1/48)
=1/3×15/48
=5/48

对(1/3n)*6n求和n从1到15

1/3×6+1/6×9+1/9×12+····+1/45×48
=1/3(1/3-1/6)+1/3(1/6-1/9)+1/3(1/9-1/12)+.......+1/3(1/45-1/48)
=1/3(1/3-1/6+1/6-1/9+1/9........-1/45+1/45-1/48)
=1/3(1/3-1/48)
=1/3(16/48-1/48)
=1/3 x 15/48
=5/48