1, thực hiện phép tính a, 15/7 . (1/5-3/10) : -1/7 - (1/3 -1/5) b, -3/4 . (1/8 -3/2) -5/4 :(1/2-5/4)-1/3

Đáp án + Giải thích các bước giải:

`a,` `15/7` `.` `(` `1/5` `-` `3/10` `)` `:` $\dfrac{-1}{7}$ `-` `(` `1/3` `-` `1/5` `)`

`=` `15/7` `.` `(` `2/30` `-` `3/30` `)` `.` `(` `-7` `)` `-` `(` `5/15` `-` `3/15` `)`

`=` `15/7` `.` $\dfrac{-1}{10}$ `.` `(` `-7` `)` `-` `2/15`

`=` $\dfrac{-3}{14}$ `.` `(` `-7` `)` `-` `2/15` 

`=` `3/2` `-` `2/15`

`=` `45/30` `-` `4/30`

`=` `41/30`

`b,` $\dfrac{-3}{4}$ `.` `(` `1/8` `-` `3/2` `)` `-` `5/4` `:` `(` `1/2` `-` `5/4` `)` `-` `1/3`

`=` $\dfrac{-3}{4}$ `.` `(` `1/8` `-` `12/8` `)` `-` `5/4` `:` `(` `2/4` `-` `5/4` `)` `-` `1/3`

`=` $\dfrac{-3}{4}$ `.` $\dfrac{-11}{8}$ `-` `5/4` `:` $\dfrac{-3}{4}$ `-` `1/3`

`=` `33/32` `-` `5/4` `.` $\dfrac{-4}{3}$ `-` `1/3`

`=` `33/32` `+` `5/3` `-` `1/3`

`=` `99/96` `+` `160/96` `-` `32/96`

`=` `227/96`