奥数简便运算:(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+.+1/9

来源:学生作业帮助网 编辑:作业帮 时间:2024/05/08 16:13:10
奥数简便运算:(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+.+1/9

奥数简便运算:(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+.+1/9
奥数简便运算:(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+.+1/9

奥数简便运算:(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+.+1/9
原式
=(1+2+3+4+5+6+7+8+9)-(1+2+3+4+5+6+7+8)/2+(1+2+3+4+5+6+7)/3-(1+2+3+4+5+6)/4+(1+2+3+4+5)/5-(1+2+3+4)/6+(1+2+3)/7
-(1+2)/8+1/9
=45-36/2+28/3-21/4+15/5-10/6+6/7-3/8+1/9
=45-18+28/3-21/4+3-5/3+6/7-3/8+1/9
=30-45/8+6/7+70/9
=30+1517/504
=33+5/504