Đáp án+Giải thích các bước giải:
`c, 12^2 - 2^3 . 4 + 8`
`= 144 - 8 . 4 + 8`
`= 144 - 32 + 8`
`= 112 + 8`
`= 120`
`d, 3 . 5^2 - 16 : 2^2`
`= 3 . 25 - 16 : 4`
`= 75 - 4`
`= 71`
`e, 5^3 : 25 . 2^4 - 4^2 + 21`
`= 125 : 25 . 8 - 16 + 21`
`= 5 . 8 - 16 + 21`
`= 40 - 16 + 21`
`= 24 + 21`
`= 45`
`f, 2^3 . 17 - 2^3 . 14`
`= 8 . 17 - 8 . 14`
`= 8 . (17 - 14)`
`= 8 . 3`
`= 24`
`Bài 5:`
`a, 70 - 5 . (x - 3) = 45`
` 5 . (x - 3) = 70 - 45`
` 5 . (x - 3) = 25`
` x - 3 = 25 : 5`
` x - 3 = 5`
` x = 5 + 3`
` x = 8`
`Vậy x = 8`
`b, 10 + 2x = 4^5 : 4^3`
` 10 + 2x = 4^2`
` 10 + 2x = 16`
` 2x = 16 - 10`
` 2x = 6`
` x = 6 : 2`
` x = 3`
`Vậy x = 3`
`c, 60 - 3(x - 2) = 51`
` 3(x - 2) = 60 - 51`
` 3(x - 2) = 9`
` x - 2 = 9 : 3`
` x - 2 = 3`
` x = 3 + 2`
` x = 5`
`Vậy x = 5`
`d, 4x - 20 = 2^5 : 2^3`
` 4x - 20 = 2^2`
` 4x - 20 = 4`
` 4x = 4 + 20`
` 4x = 24`
` x = 24 : 4`
` x = 6`
`Vậy x = 6`
