Tìm x ,y , z thuộc Q biết:|x+1/2|+|y-3/4|+|z-1|=0

$\left|x+\frac{1}{2}\right|+\left|y-\frac{3}{4}\right|+\left|z-1\right|=0$  mà $\left|x+\frac{1}{2}\right|\ge 0;\left|y-\frac{3}{4}\right|\ge 0;\left|z-1\right|\ge 0$

$\Rightarrow \left\{\begin{array}{l}\left|x+\frac{1}{2}\right|=0\\ \left|y-\frac{3}{4}\right|=0\\ \left|z-1\right|=0\end{array}\right.\Rightarrow \left\{\begin{array}{l}x+\frac{1}{2}=0\\ y-\frac{3}{4}=0\\ z-1=0\end{array}\right.\Rightarrow \left\{\begin{array}{l}x=-\frac{1}{2}\\ y=\frac{3}{4}\\ z=1\end{array}\right.$ 

Vậy $x=-\frac{1}{2}$; $y=\frac{3}{4}$; $z=1$