1-5/6+7/12-9/20+11/30-13/42+15/56-17/72简便方法怎么算
来源:百度知道 编辑:UC知道 时间:2024/07/06 21:03:42
。。。。。帮帮我
Note:5/6 = (2+3)/ ( 2*3 )= 1/2 + 1/3
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72
= 1 - 1/2 - 1/3 + 1/3 + 1/4 - 1/4 - 1/5 ……+1/8
- 1/8 - 1/9
= 1 - 1/2 - 1/9
= 18/18 - 9/18 - 1/18
= 8/18
= 4/9
= 0.44444444444444444444444444444444444
=1-(2+3)/(2*3)+(3+4)/(3*4)-(4+5)/(4*5)+(5+6)/(5*6)-(6+7)/(6*7)+(7+8)/(7*8)-(8+9)/(8*9)
=1-2/(2*3)-3/(2*3)+3/(3*4)+4/(3*4)-4/(4*5)-5/(4*5)+5/(5*6)+6/(5*6)-6/(6*7)-7/(6*7)+7/(7*8)+8/(7*8)-8/(8*9)-9/(8*9)
=1-1/3-1/2+1/4+1/3-1/5-1/4+1/6+1/5-1/7-1/6+1/8+1/7-1/9-1/8
=1-1/2-1/9
=7/18
1/1*2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7+1/7*8+1/8*9+1/9*10+1/10*11+1/11*12+1/12*13+1/13*14+1/14*15=?
1又1/2-5/6+7/12-9/20+11/30-13/42+15/56=?
求解一道小学数学题1+2*1/6+3*1/12+4*1/20+5*1/3+6*1/42+7*1/56+8*1/72+9*1/90
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72简便方法怎么算
用简便方法算:1-5/6+7/12-9/20+11/30-15/42+/17/56
3/2 5/6 7/12 9/20 ( )?
奥数题:1/2/3/4/5/6/7/8/9=2.8
1/5×1/6+1/6×1/7+1/7×1/8+1/8×1/9+1/9×1/10的简便方法是什么?
2^2/1*3+4^2/3*5+6^2/5*7+8^2/7*9+10^2/9*11+12^2/11*13
请你在3/2,5/6,7/12,9/20,11/30,13/42,15/56这些数的中间添上+或-,使等式的结果等于1又1/8