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

x+12+y−34+z−1=0  mà x+12≥0;y−34≥0;z−1≥0

⇒x+12=0y−34=0z−1=0⇒x+12=0y−34=0z−1=0⇒x=−12y=34z=1 

Vậy x=−12; y=34; z=1