1⼀1+(2⼀1-1⼀2)+(3⼀1-2⼀2+1⼀3)+(4⼀1-3⼀2+2⼀3-1⼀4)+...+(9⼀1-8⼀2+7⼀3-6⼀4+5⼀5-4⼀6+3⼀7-2⼀8+1⼀9=

1/1+(2/1-1/2)+(3/1-2/2+1/3)+(4/1-3/2+2/3-1/4)+...+(9/1-8/2+7/3-6/4+5/5-4/6+3/7-2/8+1/9
=(1+2+...+9)-(1/2+2/2+3/2+...+8/2)+(1/3+2/3+...+7/3)-...+1/9
=9(1+9)/2-(1+2+..+8)/2+(1+2+..+7)/3-..+1/9
=45-9*8/2/2+8*7/2/3-7*6/2/4+6*5/2/5-5*4/2/6+4*3/2/7-3*2/2/8+2*1/2/9
=45-18+28/3-21/4+3-5/3+6/7-3/8+1/9
=30-45/8+6/7+70/9
=

1/1+(2/1-1/2)+(3/1-2/2+1/3)+(4/1-3/2+2/3-1/4)+...+(9/1-8/2+7/3-6/4+5/5-4/6+3/7-2/8+1/9
=(1+2+...+9)-(1/2+2/2+3/2+...+8/2)+(1/3+2/3+...+7/3)-...+1/9
=9(1+9)/2-(1+2+..+8)/2+(1+2+..+7)/3-..+1/9
=45-9*8/2/2+8*7/2/3-7*6/2/4+6*5/2/5-5*4/2/6+4*3/2/7-3*2/2/8+2*1/2/9
=45-18+28/3-21/4+3-5/3+6/7-3/8+1/9
=30-45/8+6/7+70/9
=33又5/504
假分数就素16637/504
矮油~~~~算死我了 禁止抄袭哦~

拆成几部分得
原式=(1+2+3+4....+9)+(-1-2-3...-8)／2+(1+2+...7)／3+.....+1／9
=45+(-36)／2+28／3.....
=45-18+28／3-5.25+3-5／3+6／7-0.375+1／9
=2又1279／1512