a分之b+b分之a+2
=b/a+a/b+2
=(b²+a²+2ab)/ab
=(a+b)²/ab
a=根号5+2,b=根号5-2
a+b=2√5
ab=(根号5+2)(根号5-2)=5-4=1代入得
(a+b)²/ab
=(2√5)²/1
=20
希望能解决您的问题.