简单啊!题目即证:1/a+1/b<1(两边同时除以ab)因为a>2,b>2,所以:1/a+1/b<1/2+1/2=1得证!
a>2,b>2,所以a-1>1 b-1>1 (a-1)(b-1)>11<ab-a-b+1=(a-1)(b-1)a+b<ab