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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