Bài 1 : tìm x, biết a. 36 : ( x - 5 ) = 2 mũ 2 b 20 : ( 1 + x ) = 2 c. 30 - [ 4 . ( x - 2 ) + 15 ] d. [ ( 8x -12 ) : 4 ] 3 mũ 3 = 3 mũ 6 e. \(5^{x+1}+ 5 mũ x = 750\)

`a) 36 : (x - 5) = 2^2`

`=> 36 : (x - 5) = 4`

`=> x - 5 = 36 : 4`

`=> x - 5 = 9`

`=> x = 9 + 5`

`=> x = 14`

Vậy `x = 14`

`--------------`

`b) 20 : (1 + x) = 2`

`=> 1 + x = 20 : 2`

`=> 1 + x = 10`

`=> x = 10 - 1`

`=> x = 9`

Vậy `x = 9`

`-------------`

`c) 30 - [4 . (x - 2) + 15] = 3`

`=> 4 . (x - 2) + 15 = 30 - 3`

`=> 4 . (x - 2) + 15 = 27`

`=> 4 . (x - 2) = 27 - 15`

`=> 4 . (x - 2) = 12`

`=> x - 2 = 12 : 4`

`=> x - 2 = 3`

`=> x = 3 + 2`

`=> x = 5`

Vậy `x = 5`

`-------------`

`d) [( 8x - 12 ) : 4 ] . 3^3 = 3^6`

`=> (8x - 12) : 4 = 3^6 : 3^3`

`=> (8x - 12) : 4 = 27`

`=> 8x - 12 = 27 . 4`

`=> 8x - 12 = 108`

`=> 8x = 108 + 12`

`=> 8x = 120`

`=> x = 120 : 8`

`=> x = 15`

Vậy `x = 15`

`--------------`

`e) 5^(x+1) + 5^x = 750`

`=> (5+1)  . 5^x = 750`

`=> 6 . 5^x = 750`

`=> 5^x = 750 : 6`

`=> 5^x = 125`

`=> 5^x = 5^3`

`=> x = 3`

Vậy `x = 3`

$# 𝓖𝓻𝓮𝓮𝓷$