Question

(2x + 1)² = 625

Answer 1

(2x + 1)² = 625

2x + 1 = 25 hoặc 2x + 1 = -25

*) 2x + 1 = 25

2x = 25 - 1

2x = 24

x = 24 : 2

x = 12

*) 2x + 1 = -25

2x = -25 - 1

2x = -26

x = -26 : 2

x = -13

Vậy x = -13; x = 12

Answer 2

`(2x+1)^2=625`

`=>(2x+1)^2 =(+- 25)^2`

\(\Rightarrow\left[{}\begin{matrix}2x+1=25\\2x+1=-25\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}2x=24\\2x=-26\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=12\\x=-13\end{matrix}\right.\)

Answer 3

(2x + 1)2 = 625

--> (2x + 1)² = 25²

 TH1: 2x +1        = 25

    --> 2x              = 25 - 1

    --> 2x              = 24

    --> x                = 12

TH2: 2x + 1 = -25

    --> 2x       = -25 - 1

    --> 2x       = -26

    --> x         = -13 

Vậy x thuộc {12; -13}