a²+b²-4a-2b+5=0
(a²-4a+4)+(b²-2b+1)=0
(a-2)²+(b-1)²=0
a=2,b=1
a+(√a-√b)²/√ab+4√ab
=2+(√2-1)²/√2+4√2
=11√2/2