1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/424/3 - 5/6 + 7/12 -8/15 +9/205/14 +5/84 +5/204 +5/374 +5/374 +5/594 +5/8641/1+2 +1/1+2+3 + 1/1+2+3+4 + …… +1/1+2+3+……+199+200

来源:学生作业帮助网 编辑:作业帮 时间:2024/07/12 07:13:08
1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/424/3 - 5/6 + 7/12 -8/15 +9/205/14 +5/84 +5/204 +5/374 +5/374 +5/594 +5/8641/1+2 +1/1+2+3 + 1/1+2+3+4 + …… +1/1+2+3+……+199+200
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1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/424/3 - 5/6 + 7/12 -8/15 +9/205/14 +5/84 +5/204 +5/374 +5/374 +5/594 +5/8641/1+2 +1/1+2+3 + 1/1+2+3+4 + …… +1/1+2+3+……+199+200
1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42
4/3 - 5/6 + 7/12 -8/15 +9/20
5/14 +5/84 +5/204 +5/374 +5/374 +5/594 +5/864
1/1+2 +1/1+2+3 + 1/1+2+3+4 + …… +1/1+2+3+……+199+200

1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/424/3 - 5/6 + 7/12 -8/15 +9/205/14 +5/84 +5/204 +5/374 +5/374 +5/594 +5/8641/1+2 +1/1+2+3 + 1/1+2+3+4 + …… +1/1+2+3+……+199+200
1/2 - 1/6 - 1/12 - 1/20 - 1/30 - 1/42
=1/1*2-1/2*3-1/3*4-1/4*5-1/5*6-1/6*7
=1-1/2-1/2+1/3-1/3+1/4-1/4+1/5-1/5+1/6-1/6+1/7
=1/7 其他的可以抵消
4/3 - 5/6 + 7/12 -8/15 +9/20
=1+1/3-1/2-1/3+1/3+1/4-1/3-1/5+1/4+1/5
=1-1/2 +1/4+1/4 其他的可以抵消
=1/2+1/2
=1
5/14 +5/84 +5/204 +5/374 +5/374 +5/594 +5/864(中间多了5/374)
=5/2*7+5/7*12+5/12*17+5/17*22+5/22*27+5/27*32
=1/2-1/7+1/7-1/12+1/12-1/17+1/17-1/22+1/22-1/27+1/27-1/32
=1/2-1/32 其他的可以抵消
=15/32
1/1+2 +1/1+2+3 + 1/1+2+3+4 + …… +1/1+2+3+……+199+200
=2/2*3+2/3*4+2/4*5+……+2/200*201
=2×(1/2-1/3+1/3-1/4+1/4-1/5+……+1/200-1/201)
=2×(1/2-1/201)
=1-2/201
=199/201
*也表示×,打起来方便,所以用了,能看懂吗?