1/2*1/3+1/3*1/4+1/4*1/5.+1/18*1/19+1/19*1/20
2个回答
1/n*1/(n+1)=1/n-1/(n+10
所以原式=1/2-1/3+1/3-1/4+1/4*1/5.+1/18-1/19+1/19-1/20
=9/20
相关问题
1/1*2*3*4+1/2*3*4*5+1/3*4*5*6+-----+1/17*18*19*20
简算1/(2×3)+1/(3×4)+1/(4×5)+……+1/(18×19)+1/(19×20)
算式(1+1/2+1/3...+1/20)+(1+2/3+2/4+2/5..+2/20)+.+(1+18/19+18/2
1/1*2*3+1/2*3*4+1/3*4*5+.1/18*19*21=?
(2/1-3/1)+(3/1-4/1)+(4/1+5/1)+......+(19/1-20/1)=?
(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+……+(1/19-1/20)=
1/2×3+1/3*4+1/4*5+.+1/19*20=?
1/2x3十1/3x4十1/4x5十……十1/18x19十1/19x20=?
1/1x2+1/2x3+1/3x4+1/4x5+1/5x6+.+1/18x19+1/19x20 计算方法与结果
求一题的解答公式 1/(1*2*3)+1/(2*3*4)+1/(3*4*5)+.1/(18*19*20)=?