Bài 3. Thực hiện phép tính: a, 21.( – 29) + (– 17).( – 13) c, (– 143):(– 13) – (– 5).(– 12) b, (– 11)2.3 – [3 – (– 5)( – 4)] d, 17 – {(– 32) – (–3) 3

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1. Đáp án:

    

   Giải thích các bước giải:

   a) `21.( – 29) + (– 17).( – 13)`

   `= -609 + 221`

   `= -388`

   b) `(– 11).2.3 – [3 – (– 5)( – 4)]`

   `= -11 . 6 – (3 – 20)`

   `= -66 – (-17)`

   `= -49`

   c) ` (– 143):(– 13) – (– 5).(– 12)`

   `= 11 – 60`

   `= -49`

   d) `17 – {(– 32) – (–3) . 3 – [5.(– 41) – 12:(– 4)0 ]+ 1571}` 

   `= 17 – {-32 – (-9) – [-205 – (-3).0] + 1571}`

   `= 17 – [-23 – (-205 – 0) +1571]`

   `= 17 – [-23 – (-205) + 1571]`

   `= 17 – (182 + 1571)`

   `= 17 – 1753` 

   `= -1736` 

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2. `a) 21.(-29)+(-17).(-13)`

   `=-609+221`

   `=-388`

   `b) (– 11)2.3 – [3 – (– 5)( – 4)]`

   `= (– 11)2.3 – [3-20]`

   `=(– 11)2.3 – (-17)`

   `=(-22).3-(-17)`

   `=(-66)-(-17)`

   `=-49`

   `c) (– 143):(– 13) – (– 5).(– 12)`

   `=11-60`

   `=-49` 

   `d)17 – {(– 32) – (–3) 3 – [5.(– 41) – 12:(– 4)0 ]+ 1571}`

   `=17 – {(– 32) – (–3) 3 – [-205 – (-3).0 ]+ 1571}`

   `=17 – {(– 32) – (–3) 3 – [-205 – 0 ]+ 1571}`

   `=17 – {(– 32) – (–3) 3 – (-205)+ 1571}`

   `=17 – {(-29). 3 – (-205)+ 1571}`

   `=17 – {(-87) – (-205)+ 1571}`

   `=17 – {118+ 1571}`

   `=17 – 1689`

   ` =-1672`

    

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