1976

16/9

34/13

1976

16/9

34/13

1976

16/9

34/13

9976+865)+135=976+(865+135)=976+1000=1976

891+(799+109)=(891+109)+799=1000+799=1799

(2/5+1/9)+3/5=(2/5+3/5)+1/9=1+1/9=9/9+1/9=10/9

19/11+(8/13+3/11)=(19/11+3/11)+8/13=22/11+8/13=22/11+8/13=2+8/13=26/13+8/13=34/13

16.88+9.76+3.12=(16.88+3.12)+9.76=20+9.76=29.76

72.68+17.16+82.64=72.68+(17.16+82.64)=72.68+100=172.68

(976+865)+135=976+(865+135)

                      =976+1000=1976

Blox fruits V 100000000000000000

1. (976 + 865) + 135 = 976 + 865 + 135 = 976 + (865 + 135) = 975 + 1000 = 1975

891 + (799 + 109) = 891 + 799 + 109 = (891 + 109) + 799 = 1000 + 799 = 1799

(2/5 + 7/9) + 3/5 = 2/5 + 7/9 + 3/5 = (2/5 + 3/5) + 7/9 = 1 + 7/9 = 16/9

2) 1 phút = 60 giây = 1/60 giờ

   1 giây = 1/60 phút = 1/3600 giờ

2. Viết số thích hợp:

1 phút =....60.....giây =......1/60...giờ

1 giây =...1/60......phút =..1/3600.......giờ

Bài 1:

\(\left(976+865\right)+135=976+\left(865+135\right)=976+1000=1976\)

\(891+\left(799+109\right)=\left(891+109\right)+799=1000+799=1799\)

\(\left(\frac{2}{5}+\frac{7}{9}\right)+\frac{3}{5}=\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{7}{9}=1+\frac{7}{9}=\frac{16}{9}\)

\(\frac{19}{11}+\left(\frac{8}{13}+\frac{3}{11}\right)=\left(\frac{19}{11}+\frac{3}{11}\right)+\frac{8}{13}=2+\frac{8}{13}=\frac{34}{13}\)

Bài 2:

1 phút = 60 giây = \(\frac{1}{60}\)giờ

1 giây = \(\frac{1}{60}\)phút = \(\frac{1}{3600}\)giờ

~Học tốt~

bài này chắc chắn sai 100%

ai cứu với ạ

ko 

có chết đâu mà phải cứu

1,

a,=4/7:4/9.3

=9/7.3

=27/7

b,=(7/11+4/11).5/6

=1.5/6

=5/6

`(6/7-2/7):4/9xx3=4/7xx9/4xx3=[4xx9xx3]/[7xx4]=27/7`

`7/11xx5/6+4/11xx5/6=(7/11+4/11)xx5/6=11/11xx5/6=5/6`

=(1/11+10/11)+(2/11+9/11)+(3/11+8/11)+(4/11+7/11)+(5/11+6/11)

=11/11+11/11+11/11+11/11+11/11

=1+1+1+1+1

=5

=1+2+3+4+5+6+7+8+9+10 trên 11

= (1+9)+(2+8)+3+7)+(4+6)+5+10 trên 11

=10+10+10+10+10+5 trên 11

=10x5+5 trên 11

=50+5 trên 11

=55/11

=5

trên có nghĩa là (tất cả) phần 11 nha.

1/11+2/11+3/11+4/11+5/11+6/11+7/11+8/11+9/11+10/11

=(1/11+10/11)+(2/11+9/11)+(3/11+8/11)+(4/11+7/11)+(5/11+6/11)

=1+1+1+1+1

=5

chúc bạn học tốt!

a) \(1678\cdot24+77\cdot1678-1678=1678\left(24+77-1\right)=167800\)

b) Ta có: \(\dfrac{2}{5}+\dfrac{4}{11}+\dfrac{3}{5}+\dfrac{18}{11}+\dfrac{1}{4}+\dfrac{1}{6}\)

\(=\left(\dfrac{2}{5}+\dfrac{3}{5}\right)+\left(\dfrac{4}{11}+\dfrac{18}{11}\right)+\dfrac{1}{4}+\dfrac{1}{6}\)

\(=3+\dfrac{1}{4}+\dfrac{1}{6}\)

\(=\dfrac{36}{12}+\dfrac{3}{12}+\dfrac{2}{12}=\dfrac{41}{12}\)

c) \(\dfrac{7}{9\cdot7}+\dfrac{7}{9\cdot4}-\dfrac{7}{9\cdot10}\)

\(=\dfrac{7}{9}\left(\dfrac{1}{7}+\dfrac{1}{4}-\dfrac{1}{10}\right)\)

\(=\dfrac{7}{9}\cdot\left(\dfrac{20}{140}+\dfrac{35}{140}-\dfrac{14}{140}\right)\)

\(=\dfrac{7}{9}\cdot\dfrac{41}{140}=\dfrac{41}{180}\)