a: =>x+3/4=1/2 hoặc x+3/4=-1/2
=>x=-1/4 hoặc x=-5/4
b: \(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\\left(x-2-x\right)\left(x-2+x\right)=0\end{matrix}\right.\Leftrightarrow x=1\)
c: \(\Leftrightarrow\left\{{}\begin{matrix}x>=0\\\left(x+2-x\right)\left(x+2+x\right)=0\end{matrix}\right.\Leftrightarrow x\in\varnothing\)