1×2×3分之1+2×3×4分之1+3×4×5分之一×4×5×6分之一······11×12×13分之1 求过程

2024-11-28 00:55:15
推荐回答(1个)
回答1:

解:原式=[1/(1x2)-1/(2x3)]/4+[1/(2x3)-1/(3x4)]/4+[1/(3x4)-1/(4x5)]/4+…+[1/(11x12)-1/(12x13)]/4
=[1/(1x2)-1/(2x3)+1/(2x3)-1/(3x4)+1/(3x4)-1/(4x5)+…+1/(11x12)-1/(12x13)]/4
=[1/(1x2)-1/(12x13)]/4
=(77/156)/4
=77/624