Bài `1:` Tìm `x`:
`a) 3.(x-2) + 15=6`
`=> 3.(x - 2) = 6 - 15`
`=> 3.(x-2) = -9`
`=> x-2 = (-9) : 3`
`=> x-2 = -3`
`=> x = -3 + 2`
`=> x = -1`
Vậy `x=-1`
`b) -3.|2x-1| = -21`
`=> |2x-1| = -21 : (-3)`
`=> |2x-1| = 7`
`=> 2x-1=7` hoặc `2x-1=-7`
`+) 2x-1=7 <=> 2x= 8 <=> x=4`
`+) 2x-1=-7 <=> 2x = -6 <=>x=-3`
Vậy `x\in{-3;4}`
Bài `2:` Tính:
`a) 37.(-4)^2 +23.16-16.160 `
` = 37. 16 + 23. 16 - 16 .160`
` = 16. (37 + 23 - 160)`
` = 16 . (-100)`
` = -1600`
`b) (-6)/11 . 4/9 + 5/9 . (-6)/11 + 2 6/11`
` = (-6)/11 . (4/9 + 5/9) + 2 + 6/11`
` = (-6)/11 . 1 + 6/11 + 2`
` = (-6)/11 + 6/11 + 2`
` = 0 + 2`
` = 2`
`c) (-5)/7 . 2/11 + (-5)/7 . 9/11 + 5/7`
` = (-5)/7 . (2/11 + 9/11) + 5/7`
` = (-5)/7 . 1 +5/7`
` = (-5)/7 + 5/7`
` = 0`
