7/12-9/20+11/30-13/42+15/56-17/72+19/90巧算答案

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第1个回答 2022-09-17

7/12-9/20+11/30-13/42+15/56-17/72+19/90
=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
=1/3+1/10
=13/30

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7/12-9/20+11/30-13/42+15/56-17/72+19/90巧算答案答：7/12-9/20+11/30-13/42+15/56-17/72+19/90 =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 =1/3+1/10 =13/30

7/12-9/20+11/30-13/42+15/56-17/72+19/90怎么做答：=(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)=1/3-1/10 =7/30

7/12-9/20+11/30-13/42+15/56-17/72+19/90巧算答案答：7/12-9/20+11/30-13/42+15/56-17/72+19/90 =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 =1/3+1/10 =13/30

7/12-9/20+11/30-13/42+15/56-17/72答：7/12-9/20+11/30-13/42+15/56-17/72 =1/3+1/4-（1/4+1/5）+（1/5+1/6）-（1/6+1/7）+（1/7+1/8）-（1/8+1/9）=1/3-1/9 =2/9 ps:以后提问不要出现“快！”之类的催促性的话，这是很不友好的！好歹也要说“我很急”这样子谦虚点的话吧 ...

7/12-9/20+11/30-13/42+15/56-17/72简便方法计算?答：计算 7/12-9/20+11/30-13/42+15/56-17/72 =(1/3+1/4)-(1/4+1/5)+(1/5+1/6)-(1/6+1/7)+(1/7+1/8)-(1/8+1/9)=1/3-1/9 =3/9-1/9 =2/9

7/12-9/20+11/30-13/42+15/56-17/72+19/90=?答：7/12-9/20+11/30-13/42+15/56-17/72+19/90 =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 =1/3+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 =1/3+1/10 =10/30+3/30 =13/30 ...

数学题7/12-9/20+11/30-13/42+15/56-17/72+19/90怎样做?求解释答：=(3+4)/3*4 - (4+5)/4*5 + (5+6)/5*6 - (6+7)/6*7 +(7+8)/7*8 -(8+9)/8*9 +(9+10)/9*10 =3/3*4+4/3*4 - 4/4*5 -5/4*5 。。。+9/9*10+10/9*10 =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 =1/3+...

7/12-9/20+11/30-13/42+15/56-17/72+19/90(/是分数线)答：7/12-9/20+11/30-13/42+15/56-17/72+19/90 =(3/12+4/12)-(4/20+5/20)+(5/30+6/30)-(6/42+7/42)+(7/56+8/56)-(8/72+9/72)+(9/90+10/90)=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 =1/3+1/10 =13/30 ...

简算7/12-9/20+11/30-13/42+15/56-17/72答：7/12-9/20+11/30-13/42+15/56-17/72 =1/3+1/4-（1/4+1/5）+（1/5+1/6）-（1/6+1/7）+（1/7+1/8）-（1/8+1/9）=1/3-1/9 =2/9 ps:以后提问不要出现“快!”之类的催促性的话,这是很不友好的!好歹也要说“我很急”这样子谦虚点的话吧 ...

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