-2/5.3/4+-2/5.(1/2)^2 19/25.(3/7+25/19)-3/7 (19/25-7/3)

Đáp án + Giải thích các bước giải:

`a) {-2}/5. 3/4 + {-2}/5. (1/2)^2`

`= {-2}/5. 3/4 + {-2}/5. 1/4`

`= {-2}/5. (3/4 + 1/4)`

`= {-2}/5. 1`

`= {-2}/5`

`b) 19/25. (3/7 + 25/19) - 3/7. (19/25 - 7/3)`

`= 19/25. 3/7 + 19/25. 25/19 - 3/7. 19/25 + 3/7. 7/3`

`= (19/25. 3/7 - 3/7. 19/25) + (19/25. 25/19 + 3/7. 7/3)`

`= 0 + (1 + 1)`

`= 2`

`(-2)/5 . 3/4 + (-2)/5 . (1/2)^2`

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

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

`= (-2)/5 . 1`

`= (-2)/5`

`...`

`19/25 . (3/7 + 25/19) - 3/7 . (19/25 - 7/3)`

`= 19/25 . 3/7 + 19/25 . 25/19 - 3/7 . 19/25 + 3/7 . 7/3`

`= (19/25 . 3/7 - 3/7 . 19/25) + (19/25 . 25/19 + 3/7 . 7/3 )`

`= 19/25 . 25/19 + 3/7 . 7/3`

`= 1 + 1`

`= 2`

`#dtkc`