#wheijx.

`1/4 - (2x+1/2)^2 = 0`

`<=> (1/2)^2 - (2x+1/2)^2 = 0`

`<=> (1/2 - 2x - 1/2)(1/2+2x+1/2) = 0`

`<=> -2x(1+2x) = 0`

`<=>` $\left[\begin{matrix} -2x=0\\ 1+2x=0\end{matrix}\right.$

`<=>` $\left[\begin{matrix} x=0\\ 2x=-1\end{matrix}\right.$

`<=>` $\left[\begin{matrix} x=0\\ x=\dfrac{-1}{2}\end{matrix}\right.$

Vậy `x in {0 ; -1/2}`.