Giúp mình làm với hứa trả đủ

Đáp án:

Giải thích các bước giải:

 Bài `4` :

`A)`

` - 8 + 9 ( 5/3x + 2 . 2024^0 ) = 0 `

` 9 ( 5/3x + 2 . 1 ) = 0 + 8 `

` 9 ( 5/3x + 2 ) = 8 `

` 5/3x + 2 = 8/9 `

` 5/3x = 8/9 - 2 `

` 5/3x = - 10/9 `

` x = - 10/9 : 5/3 `

` x = - 10/9 . 3/5 `

` x = - 30/45 `

` x = - 2/3 `

Vậy ` x = - 2/3 `

``

` B)`

` ( 2x - 3 )^2 + 1 3/4 = 23/4 `

` ( 2x - 3 )^2 + 7/4 = 23/4 `

` ( 2x - 3 )^2 = 23/4 - 7/4 `

` ( 2x - 3 )^2 = 16/4 `

` ( 2x - 3 )^2 = 4 `

` ( 2x - 3 )^2 = ( +- 2 )^2 `

` 2x - 3 = 2 ` hoặc `2x - 3 = - 2 `

``

`TH1`

` 2x - 3 = 2 `

` 2x = 2 + 3 `

` 2x = 5 `

` x = 5/2 `

``

`TH2`

` 2x - 3 = - 2 `

` 2x = - 2 + 3 `

` 2x = 1 `

` x = 1/2 `

Vậy ` x = 5/2 ` hoặc ` x = 1/2 `

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

Bài `5` :

` A = 1/3 + 1/(3^2) + 1/(3^3) + ......... + 1/(3^99) ` 

` 3A =  ( 1 + 1/3 + 1/(3^2) + .... + 1/(3^98) ) `

` 3A - A =  1 + 1/3 + 1/(3^2) + ....... + 1/(3^98) - ( 1/3 + 1/(3^2) + 1/(3^3) + ..... + 1/(3^99) ) `

` 2A = 1 + 1/3 + 1/3^2 + ...... + 1/98 - 1/3 - 1/(3^2) - 1/(3^3) - ....... - 1/(3^99) `

` 2A = ( 1 - 1/(3^99) )  < 1 `

`-> 2A < 1 `

`-> A < 1/2`

`-> dpcm`