根号五加二分之根号五减二加根号五减二分之根号五加二

Question

分母有理化中分母是怎么化没的

Answer 1

根号五加二分之根号五减二加根号五减二分之根号五加二
=（√5-2）/（√5+2）+（√5+2）/（√5-2）
=(√5-2)²/[(√5+2)(√5-2)]+(√5+2)²/[(√5-2)(√5+2)]
=(5-4√5+2)/(5-4)+(5+4√5+2)/(5-4)
=7-4√5+7+4√5
=14