∵y<√(x-4)+√(4-x)+1
∴x-4≥0,4-x≥0
∴x-4=0,x=4
∴y<1
∴y-1<0
∴√(y²-2y+1)/(y-1)+|1-y|+y
=√(y-1)²/(y-1)+|y-1|+y
=|y-1|/(y-1)+|y-1|+y
=-(y-1)/(y-1)-(y-1)+y
=-1-y+1+y
=0