由2/x+1/y=1两边同时乘以xy,得2y+x=xy,又2y+x≥2√(2xy),即xy≥2√(2xy),由于x>0,y>0,
故两边同时除以√(xy),得√(xy)≥2√2,故xy≥8,即2y+x≥8.
x+2y>m²+2m,即m²+2m