∵x>0,y>0
∴8/y+1/x=1
∴x+y
=(x+y)×1
=(x+y)·(8/y+1/x)
=8·x/y+1+8+y/x
=9+8·x/y+y/x
≥9+2√(8·x/y·y/x)
=9+4√2
即最小值为9+4√2,当且仅当x=2√2+1,y=8+2√2时等号成立
∵x>0,y>0
∴8/y+1/x=1
∴x+y
=(x+y)×1
=(x+y)·(8/y+1/x)
=8·x/y+1+8+y/x
=9+8·x/y+y/x
≥9+2√(8·x/y·y/x)
=9+4√2
即最小值为9+4√2,当且仅当x=2√2+1,y=8+2√2时等号成立