(2x-1)²=49 giải giúp

`(2x-1)^2=49`

`(2x-1)^2=(`$\pm$`7)^2`

`->2x-1=`$\pm$7

`TH1:`

`2x-1=7`

`2x=8`

`x=8:2`

`x=4`

`TH2:`

`2x-1=-7`

`2x=-7+1`

`2x=-6`

`x=-6:2`

`x=-3`

`->` Vậy `x` $\in$ `{4;-3}`

` ( 2x - 1 )^2 = 49 `

` ( 2x - 1 )^2 = ( ±7 )^2 `

` 2x - 1 = ±7 `

` ⇒ ` $\left[\begin{matrix} 2x - 1 = 7 \\ 2x - 1 = -7 \end{matrix}\right.$

` ⇒ ` $\left[\begin{matrix} 2x = 8 \\ 2x = -6 \end{matrix}\right.$

` ⇒ ` $\left[\begin{matrix} x = 4 \\ x = -3  \end{matrix}\right.$

Vậy ` S = { 4 ; -3 } `