∵log3(x)＋log3(y)≥2√log3(x)log3(y) 且log3(x)log3(y)=9
∴log3(x)＋log3(y)≥6
∵log3(x)＋log3(y)=log3(xy)≥6且xy＞1
∴log3(x)＋log3(y)=log3(xy)≥log3（216）
∴xy最小值为216