Đáp án+Giải thích các bước giải:
`a, 230 + [2^4 + (x - 5)] = 315 . 2018^0`
` 230 + [16 + (x - 5)] = 315 . 1`
` 230 + [16 + (x - 5)] = 315`
` 16 + (x - 5) = 315 - 230`
` 16 + (x - 5) = 85`
` x - 5 = 85 - 16`
` x - 5 = 69`
` x = 69 + 5`
`Vậy x = 74`
`b, 707 : [(2^x - 5) + 74] = 4^2 - 3^2`
` 707 : [(2^x - 5) + 74] = 16 - 9`
` 707 : [(2^x - 5) + 74] = 7`
` (2^x - 5) + 74 = 707 : 7`
` (2^x - 5) + 74 = 101`
` 2^x - 5 = 101 - 74`
` 2^x - 5 = 27`
` 2^x = 27 + 5`
` 2^x = 32`
` 2^x = 2^5`
`⇒ x = 5`
`Vậy x = 5`
`c, [(6x - 12) : 3] . 32 = 64`
` (6x - 12) : 3 = 64 : 32`
` (6x - 12) : 3 = 2`
` 6x - 12 = 2 . 3`
` 6x - 12 = 6`
` 6x = 6 + 12`
` 6x = 18`
` x = 18 : 6`
` x = 3`
`Vậy x = 3`
`d, (x : 7 + 15) . 23 = 391`
` x : 7 + 15 = 391 : 23`
` x : 7 + 15 = 17`
` x : 7 = 17 - 15`
` x : 7 = 2`
` x = 2 . 7`
` x = 14`
`Vậy x = 14`
