Giúp mik với mụi ngừi ơi

1, `2^(x + 1) = 128`

    `2^(x + 1) = 2^7`

`=> x + 1 = 7`

`=> x  = 7 - 1`

`=> x = 6`

2, `7^x + 7^(x + 1) = 56`

    `7^x . 1 + 7^x . 7 = 56`

    `7^x . (1 + 7) = 56`

    `7^x . 8 = 56`

    `7^x = 56 : 8`

    `7^x = 7^1`

`=> x = 1`

3, `5 . 2^(x + 2) - 17 . 2^x = 48`

    `5 . 2^x . 4 - 17 . 2^x = 48`

    `2^x . (5 . 4 - 17) = 48`

    `2^x . (20 - 17) = 48`

    `2^x . 3 = 48`

    `2^x = 48 : 3`

    `2^x = 16`

    `2^x = 2^4`

`=> x = 4`

4, `3^x + 3^(x + 1) + 2 . 3^(x + 2) = 11^12 : 11^11 + 55`

   `3^x . 1 + 3^x . 3 + 2 . 3^x . 9 = 11 + 55`

   `3^x . (1 + 3 + 2 . 9) = 66`

   `3^x . 22 = 66`

   `3^x = 66 : 22`

   `3^x = 3^1`

`=> x = 1`