Question

1/√5+2-（√5-2）^2+√20的值为_

把过程写一下 √为根号^2为平方 √5+2不是√（5+2） 坐等答案 好的在加20分

Answer 1

题目是这样吧？
1/（√5+2）-（√5-2）²+√20
=√5-2-（√5-2）²+2√5
=-（√5-2）²-2+3√5
=-5+4√5-4-2+3√5
=7√5-11

Answer 2

解：
1/(√(5+2)-(√5-2)²+√20
=(√5-2)/(√5+2)(√5-2)-[(√5)²-4√5+4]+2√5
=(√5-2)-(5-4√5+4)+2√5
=√5-2-5+4√5-4+2√5
=7√5-11

Answer 3

=√5/5+2-（5-4√5+4）+2√5
=√5/5+10√5/5+2-5+4√5-4
=11√5/5-7+4√5
=11√5/5-7+20√5/5

=31√5/5-7

Answer 4

1/√5+2-（√5-2）^2+√20
=√5/5+2-(5-4√5+4)+2√5
=√5/5+4√5+2√5+2-9
=31√5/5-7