1楼:匿名用户
5/6-7/12+9/20-11/30+13/42-15/56+17/72
=(1/2+1/3)-(1/3+1/4)+(1/4+1/5)-(1/5+1/6)+(1/6+1/7)-(1/7+1/8)+(1/8+1/9)
=1/2+1/9
=11/18
2楼:匿名用户
原式=1/2+1/3-(1/3+1/4)+1/4+1/5-(1/5+1/6)+1/6+1/7-(1/7+1/8)+1/8+1/9
=1/2+1/9
=11/18
5/6-7/12+9/20-11/30+13/42-15/56+17/72
3楼:匿名用户
=1/2+1/9
=11/18
4楼:林居巧
分母拆分成连续自然数,合并得5/2-17/9=11/18
5楼:****天蝎
26/63 不知道有没有算错
5/6-7/12+9/20-11/30+13/42-15/56+17/72
6楼:穗子和子一
=1/2+1/9
=11/18
1又3分之1-7/12+9/20-11/30+13/42-15/56+17/72等于多少
7楼:匿名用户
(1+1/3)-7/12+9/20-11/30+13/42-15/56+17/72
=1+1/3-(1/3+1/4)+(1/4+1/5)-(1/5+1/6)+(1/6+1/7)-(1/7+1/8)+(1/8+1/9)
=1+1/9
=10/9
5/6-7/12+9/20-11/30+13/42-15/56+17/72-19/90=
8楼:匿名用户
5/6-7/12+9/20-11/30+13/42-15/56+17/72-19/90
=1/2+1/3-(1/3+1/4)+1/4+1/5-(1/5+1/6)+1/6+1/7-(1/7+1/8)+1/8+1/9-(1/9+1/10)
=1/2-1/10
=5/10-1/10
=2/5
注:5/6=5/(2×3)=1/2+1/3
7/12——9/20+11/30——13/42+15/56——17/72 有什么简便方法吗 谢谢
9楼:匿名用户
你认真看每个分母:12=3*4 20=4*5 30=5*6 42=6*7 56=7*8 72=8*9
然后你很快发现:3+4=7 4+5=9 。。。。。
所以你可以用1/3+1/4-(1/4+1/5)-(1/5+1/6)-(1/6+1/7)-(1/8+1/7)-(1/8+1/9) 然后相同去掉 就可以得到答案了
答案是2/9
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90=?简便运算
10楼:匿名用户
1-5/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1/6+7/12-9/20+11/30-13/42+15/56-17/72+19/90
=1/2+1/10
=(5+1)/10
=6/10
=3/5
3/2-5/6+7/12-9/20+11/30-13/42+15/56-17/72=
11楼:
3/2-5/6+7/12-9/20+11/30-13/42+15/56-17/72
=(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+1/8)-(1/8+1/9)
=1-1/9
=8/9
6-7 12+9 20-11 30+13
1楼 匿名用户 5 6 7 12 9 20 11 30 13 42 1 4 9 20 11 30 13 42 1 4 1 12 13 42 1 3 13 42 9 14 5 6 7 12 9 20 11 30 13 42 15 56 17 72 19 90 2楼 匿名用户 5 6 7 12 9 20...