1/5 . 2^x + 1/3 . 2^{x + 1} = 1/5 . 2^7 + 1/3 . 2^8 29/09/2021 Bởi Hadley 1/5 . 2^x + 1/3 . 2^{x + 1} = 1/5 . 2^7 + 1/3 . 2^8
`1/5 . 2^x + 1/3. 2^(x+1) = 1/5. 2^7 + 1/3. 2^8` => ` 1/5 . 2^x + 1/3. 2^(x+1) = 2^7( 1/5+ 1/3 .2)` => ` 2^x( 1/5 + 1/3. 2) = 2^7( 1/5 + 1/3 .2)` => `2^x = 2^7( 1/5 + 1/3 .2): (1/5 + 1/3 .2)` => `2^x = 2^7` => `x= 7` Vậy `x= 7` Bình luận
Đáp án: `x=7` Giải thích các bước giải: `1/5 . 2^x + 1/3 . 2^{x + 1} = 1/5 . 2^7 + 1/3 . 2^8` `\to1/5 . 2^x +1/3 . 2^x . 2 =1/5 . 2^7 + 1/3 . 2^7 . 2` `\to1/5 . 2^x +2^x . 2/3=1/5 . 2^7 +2^7 . 2/3` `\to2^x (1/5+2/3)=2^7 (1/5+2/3)` `\to2^x=2^7` `\tox=7` Vậy `x=7` Bình luận
`1/5 . 2^x + 1/3. 2^(x+1) = 1/5. 2^7 + 1/3. 2^8`
=> ` 1/5 . 2^x + 1/3. 2^(x+1) = 2^7( 1/5+ 1/3 .2)`
=> ` 2^x( 1/5 + 1/3. 2) = 2^7( 1/5 + 1/3 .2)`
=> `2^x = 2^7( 1/5 + 1/3 .2): (1/5 + 1/3 .2)`
=> `2^x = 2^7`
=> `x= 7`
Vậy `x= 7`
Đáp án:
`x=7`
Giải thích các bước giải:
`1/5 . 2^x + 1/3 . 2^{x + 1} = 1/5 . 2^7 + 1/3 . 2^8`
`\to1/5 . 2^x +1/3 . 2^x . 2 =1/5 . 2^7 + 1/3 . 2^7 . 2`
`\to1/5 . 2^x +2^x . 2/3=1/5 . 2^7 +2^7 . 2/3`
`\to2^x (1/5+2/3)=2^7 (1/5+2/3)`
`\to2^x=2^7`
`\tox=7`
Vậy `x=7`