Đáp án`+`Giải thích các bước giải:

 ` a, `

` ( x - 2)^2 - 5(x - 2 ) = 0 `

` <=> ( x - 2 )(x-2 ) - 5(x-2) = 0 `

` <=> ( x - 2 ) ( x - 2 - 5 ) = 0 `

` <=> ` $\left[\begin{matrix} x-2=0\\ x-7=0\end{matrix}\right.$

` <=> ` $\left[\begin{matrix} x=2\\ x=7\end{matrix}\right.$

Vậy ` x = { 2, 7 } `

` b, ` 

` ( 3 - 4x )^2 - 3(4x - 3 ) = 0 `

` <=> ( 4x - 3 )( 4x - 3 ) - 3 ( 4x - 3 ) = 0 `

` <=> ( 4x - 3 )( 4x - 3 - 3 ) = 0 `

` <=> ` $\left[\begin{matrix} 4x -3 =0\\ 4x-6=0\end{matrix}\right.$

` <=> ` $\left[\begin{matrix} x=3/4\\ x=3/2\end{matrix}\right.$

Vậy ` x = { 3/4, 3/2 } `

` c, `

` ( 2x - 3)^2 - (2x-3) (2x+3) = 0 `

` <=> ( 2x - 3 )( 2x -3 ) - (2x - 3 )(2x + 3) = 0 `

` <=> ( 2x - 3 )( 2x - 3 - 2x - 3 ) = 0` 

` <=> ( 2x - 3 ).(-6) = 0 `

` <=> 2x - 3 =0 `

` <=> x = 3/2 ` 

Vậy ` x = 3/2 `

` d, `

` ( x-5) ( x + 5 ) - 15x + 75 = 0 `

` <=> x^2 - 5^2 - 15x + 75 = 0 `

` <=> x^2 - 25 - 15x + 75 = 0`

` <=> x^2 - 15x + 50 = 0 `

` <=> ( x - 10 )(x - 5 ) = 0 `

` <=> ` $\left[\begin{matrix} x - 10 =0\\  x-5=0\end{matrix}\right.$

` <=> ` $\left[\begin{matrix} x = 10\\  x=5\end{matrix}\right.$

Vậy ` x = { 10, 5 } `