tinh thuan tien : a ) (21/31+ -16/7) + (44/53+10/31) +9/53 b) 31/33 - (7/32 +8/23 ) c) 38/45 - ( 8/45 - 17/51 - 3/11 ) help meeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

Giải thích các bước giải:

`a, (21/31 + (-16/(7) ) + ( 44/53  + 10/31 ) + 9/53`

`= 21/31 + (-16/(7) + 44/53  + 10/31 + 9/53`

`= ( 21/31 + 10/31) + (44/53 + 9/53) - 16/7`

`= 1 + 1 - 16/7`

`= 2 - 16/7`

`= -2/7`

`b, 31/33 - ( 7/32 + 8/23)`

Sửa : `31/23 - ( 7/32 + 8/23)`

` = 31/23 - 7/32 - 8/23`

`= (31/23 - 8/23) - 7/32`

`= 1 - 7/32`

`= 25/32`

`c, 38/45 - ( 8/45 - 17/51 - 3/11)`

`= 38/45 - 8/45 + 17/51 + 3/11`

`= ( 38/45 - 8/45)+ 1/3 + 3/11`

`= 30/45 + 1/3 + 3/11`

`= 2/3 + 1/3 + 3/11`

`= 1 + 3/11`

` = 14/11`

a) ( $\dfrac{21}{31}$ + $\dfrac{-16}{7}$ ) + ( $\dfrac{44}{53}$ + $\dfrac{10}{31}$ ) + $\dfrac{9}{53}$

= ( $\dfrac{21}{31}$ + $\dfrac{10}{31}$ ) + ( $\dfrac{44}{53}$+ $\dfrac{9}{53}$ ) + $\dfrac{-16}{7}$

= 1 + 1 + $\dfrac{-16}{7}$

= 2 + $\dfrac{-16}{7}$

=  $\dfrac{-2}{7}$ 

b) $\dfrac{31}{23}$ - ( $\dfrac{7}{32}$ + $\dfrac{8}{23}$ ) 

= $\dfrac{31}{23}$ - $\dfrac{8}{23}$ - $\dfrac{7}{32}$

= $\dfrac{23}{23}$ - $\dfrac{7}{32}$

= 1 - $\dfrac{7}{32}$

= $\dfrac{25}{12}$ 

c) $\dfrac{38}{45 }$ - ( $\dfrac{8}{45 }$ - $\dfrac{17}{51 }$ - $\dfrac{3}{11 }$ ) 

= $\dfrac{38}{45 }$ -  $\dfrac{8}{45 }$ + $\dfrac{17}{51 }$ + $\dfrac{3}{11 }$ ) 

= $\dfrac{30}{45 }$ + $\dfrac{17}{51 }$ + $\dfrac{3}{11 }$ 

= $\dfrac{2}{3}$ + $\dfrac{1}{3}$ + $\dfrac{3}{11 }$ 

= 1 + $\dfrac{3}{11 }$ 

=  $\dfrac{14}{11 }$