Bài 1 : Tìm số nguyên x biết : a) $2^{x}$ `:` $2^{5}$ `= 32 : 8` b) `23.75 + 25.23 + 100` Bài 2 : Tìm x ∈ Z biết: a) `( 2x – 8 ) . 2 =` $2^{5}$ b)

Đáp án:

 Bài 2:

a) `( 2x – 8 ).2 =` $2^{5}$ 
`( 2x – 8 ).2 = 32`
`( 2x – 8 )   = 32 : 2`
`( 2x – 8 )   = 16`
`  2x         = 16 + 8`
`  2x         = 24`
   `x         = 24 : 2`
   `x         = 12`
Vậy `x = 12`

b) `125 – 3 . ( x + 2 ) = 65`
      `3 . ( x + 2 ) = 125 – 65`
      `3 . ( x + 2 ) = 60`
          `( x + 2 ) = 60 : 3`
          `( x + 2 ) = 20`
            `x       = 20 – 2`
            `x       = 12`
Vậy `x = 12`

c) `541 + ( 218 – x ) = 735`
      `( 218 – x ) = 735 – 541`
      `( 218 – x ) = 194`
              `x   = 194 + (-218)` 
              `x   = -24`
Vậy `x = 24`

$3.$

`( 1 + 2 + `$2^{2}$`+` $2^{3}$ $+$ $2^{4}$ $+$ $2^{5}$ $+$ $2^{6}$ $+$ $x^{2}$ $2^{7}$ $+$ $2^{8}$ $+$ $2^{9}$ `)`

$=$ `( 1 + 2 )` + ( `$2^{2}$`+` $2^{3}$ ) $+$ ( $2^{4}$ $+$ $2^{5}$ ) $+$ ( $2^{6}$ $+$ $2^{7}$ )
$+$ ( $2^{8}$ $+$ $2^{9}$ )
`=` `( 1 + 2 )` `+` $2^{2}$ $.$ `( 1 + 2 )` $+$ $2^{4}$ $.$ `( 1 + 2 )` `+` $2^{8}$ $.$ `( 1 + 2 )` 
`= 3 +` $2^{2}$ $.$ $3$ $+$ $2^{4}$ `. 3`
`= 3 . (` $2^{2}$ `+` $2^{4}$ `+` $2^{6}$ `+` $2^{8}$ `)` $⋮$ $3$

P/s : Đọc chi tiết trước khi báo cáo !