1:tính nhanh: 17.43-16.7+13.17 2:tìm x: 2.(x-3)=8 6-(x-3)=4 8-2x.(x-2)=4 (2+11+x):3=8

2 câu trả lời

1.

17.43-16.7+13.7

=17.(43+13)-112

=17.56-56.2

=56.(17-2)

=56.15

=840

2.

2.(x-3)=8

x-3=4

x=7

6-(x-3)=4

x-3=2

x=5

8-2(x-2)=4

2(x-2)=4

x-2=2

x=4

(2+11+x):3=8

13+x=24

x=11

`1.`

    `17.43-16.7+13.17`

 ` =  17. ( 43 +13  ) - 112 `

  `= 17.  56  - 112`

 ` = 17.56 - 56 . 2`

 ` = 56 . ( 17-  2 )`

 `= 56 .  15`

` = 840`

 `2.`

 `2.(x-3)=8`

 `x - 3 = 8 : 2`

 `x - 3 =4`

 `x = 4 + 3`

 `x  =7`

_  _ _ _ __ _ _ _ _ _ _ _ _ _  _ _ _

 `6-(x-3)=4`

 `x - 3=  6 - 4`

 `x - 3 = 2`

 `x = 2 + 3`

 `x = 5`

  _ _ _ _ __ _ _ _ _ _ _ _ _ _  _ _ _

 `8-2.(x-2)=4`

 `2.(x-2)= 8 - 4`

 `2 . ( x -2 )  = 4`

 `x - 2 = 4 : 2`

 `x  -2 = 2`

 `x=  2+ 2`

 `x = 4`

 _  _ _ _ __ _ _ _ _ _ _ _ _ _  _ _ _

 `(2+11+x):3=8`

 `13 + x = 8 . 3`

 `13 + x = 24`

 `x = 24 - 13`

 `x = 11`

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