a²+b² -2a-4b+5 = 0
(a²-2a+1)+(b²-4b+4)=0
(a-1)²+(b-2)²=0
din (a-1)²=0 => a=1
din (b-2)²=0 => b=2
1^2005+(2-1)^2005=1+1=2