Theo t/c dãy tỉ số = nhau:
\(\frac{x-1}{2005}=\frac{3-y}{2006}=\frac{x-1+3-y}{2005+2006}=\frac{x-y+2}{4011}=\frac{4009+2}{4011}=\frac{4011}{4011}=1\)
=> \(\frac{x-1}{2005}=1\Rightarrow x-1=2005\Rightarrow x=2005+1=2006\)
=> \(\frac{3-y}{2006}=1\Rightarrow3-y=2006\Rightarrow y=3-2006=-2003\)
Vậy x=2006; y=-2003.