Bài 1: a)Tính -60:{[(12-3).2]+2} b)Tìm x -70-5.(x-3)=45 -10+2.x=4^5:4^3

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1. Bài 1:

   a) `-60:{[(12-3).2]+2}`

   `=-60:{[9.2]+2}`

   `=-60:{18+2}`

   `=-60:20=-3`

   b) $-70-5.(x-3)=45$

   $↔5.(x-3)=-115$

   $↔x-3=-23$

   $↔x=-23+3=-20$

   c) $-10+2x=4^5:4^3$

   $↔-10+2x=4^2=16$

   $↔2x=26$

   $↔x=13$

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2. Bài `1` :

   `a)`

   `-60 :{[(12 – 3).2]+2}`

   `= -60 :{[9.2] + 2}`

   `= -60 :{18 + 2}`

   `= -60 : 20`

   `= -3`

   `b)`

   `-70 – 5.(x – 3) = 45`

   `5.(x – 3) = -70 – 45`

   `5.(x -3) = -115`

   `x – 3 =  -115 : 5`

   `x  – 3 =  – 31`

   `x = -31 + 3`

   `x =28`

   ` – – — – – – — `

   `-10 + 2.x = 4^5 : 4^3`

   `-10 + 2.x  =4^2`

   `-10 + 2.x = 16`

   `2.x = 16 – (-10)`

   `2x = 26`

   `x = 26 : 2`

   `x = 13`

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