làm onw làm giúp hết tất cả mọi ý

@HoangViett

`a, 47x + 52x + x = 4*75`

`=> 47x+52x+1x=300`

`=> (47+52+1)x = 300`

`=> 100x = 300`

`=> x = 300 : 100`

`=> x = 3`

Vậy `x = 3`.

`b, [1824-(526+2x)] + 318 = 1420`

`=> 1824 - (526+2x) = 1420 - 318`

`=> 1824 - (526+2x) = 1102`

`=> 526+2x=1824-1102`

`=> 526+2x=722`

`=> 2x = 722-526`

`=> 2x = 196`

`=> x = 196 : 2`

`=> x = 98`

Vậy `x = 98`.

`c, 5225: [215-(3x-18)] = 25`

`=> 215 - (3x-18) = 5225 : 25`

`=> 215-(3x-18)=209`

`=> 3x - 18 = 215-209`

`=> 3x-18=6`

`=> 3x=6+18`

`=> 3x = 24`

`=> x = 24:3`

`=> x = 8`

Vậy `x=8`.

`d, 27 < 3^x < 243`

`=> 3^3 < 3^x < 3^5`

`=> 3 < x < 5`

Vậy `3 < x < 5`.