`1/2:3/4+5/6:3/4-2/8:3/4`

`=1/2 xx 4/3 + 5/6 xx 4/3 - 2/8 xx 4/3`

`=4/3 xx ( 1/2 + 5/6 - 2/8)`

`=4/3 xx ( 1/2 + 5/6 - 1/4 )`

`=4/3 xx ( 6/12 + 10/12 - 3/12)`

`=4/3 xx ( 16/12 - 3/12)`

`=4/3 xx 13/12`

`=13/9`

\(\frac{11}{23}+\frac{3}{23}+\frac{9}{23}=\left(\frac{3}{23}+\frac{9}{23}\right)+\frac{11}{23}=\frac{12}{23}+\frac{11}{23}=1\)

\(\frac{2}{9}+\frac{1}{18}+\frac{3}{18}=\frac{2}{9}+\left(\frac{1}{18}+\frac{3}{18}\right)=\frac{2}{9}+\frac{2}{9}=\frac{4}{9}\)

Tk cho mk nha 

ngai lam

tk nha

1. 

= 10 000 - 29 x 11

= 10 000 - 319

= 9681

2.

= ( 3/7 + 4/7 ) + ( 4/9 + 5/9 )

= 1 + 1

= 2

Bài 2 

a.8/15+7/4+7/15+5/4

=8/15+7/15+7/4+5/4

=15/15+12/4

=1+3

=4

b.98,54-(41,82-35,72)

=98,54-6,1

=92,44

Bài 1 

a) 7/8 + 1 -  3/4 = 9/8

b) 15/4 - 3/8 - 1/6 = 5/6

kết bn nhá

\(28+35+62+95+73+69+27+1\)

\(=\left(28+62\right)+\left(35+95\right)+\left(73+27\right)+\left(69+1\right)\)

\(=90+130+100+70=390\)

(28+62)+(35+95)+(73+27)+(69+1)=

90+130+100+70=390

Đs:390

   28 + 35 + 62 + 95 + 73 + 69 + 27 + 1

= (28 + 62) + (35 + 95) + (73 + 27) + (69 + 1)

=      90       +     130     +    100       +      70

=           (90 + 100)        +         (130 + 70)

=               190               +               200

=                                 390

1+ 1 /3+1/9+1/27+1/81+1/243+1/729.
Đặt:
S = 1 + 1/3 + 1/9 + 1/27 + 1/81 + 1/243 
Nhân S với 3 ta có:
S x 3 = 3 +1+ 1/3 + 1/9 + 1/27 + 1/81
Vậy: 
S x 3 - S = 3 - 1/243
2S = 728/243
S = 364/243

tick đúng nha

=364/243

đà đà na đa

= 1 x 27/3x27 + 1x9/9x9 + 1x3 / 27 x 3 + 1/81

=27/81 + 9/81 + 3/81 + 1/81

= 40/81

 3,6 x 18 + 0,6 x 12 + 0,9 x 320

=3,6 x 18 + 0,6 x 6 x 2 + 0,9 x 4 x 80

=3,6 x 18 + 3,6 x 2 + 3,6 x 80

=3,6 x (18 + 2 + 80)

=3,6 x 100

=360

Tick choa tớ nha :3