Question

(1+ 5-căn5/1 - căn5 )(5 +căn5/1+căn5 +1)

giúp mình vs ạ.mình c.on trc

Answer 1

\(=\left(1-\dfrac{\sqrt{5}\left(\sqrt{5}-1\right)}{\sqrt{5}-1}\right)\left(\dfrac{\sqrt{5}\left(\sqrt{5}+1\right)}{\sqrt{5}+1}+1\right)\)

=(1-căn 5)(1+căn 5)

=1-5

=-4

Answer 2

\(\left(1+\dfrac{5-\sqrt{5}}{1-\sqrt{5}}\right)\left(\dfrac{5+\sqrt{5}}{1+\sqrt{5}}+1\right)\)

\(=\left(1-\dfrac{\sqrt{5}\left(\sqrt{5}-1\right)}{\sqrt{5}-1}\right)\left(\dfrac{\sqrt{5}\left(\sqrt{5}+1\right)}{\sqrt{5}+1}+1\right)\)

\(=\left(1-\sqrt{5}\right)\left(\sqrt{5}+1\right)\)

\(=1^2-\left(\sqrt{5}\right)^2\)

\(=1-5\)

\(=-4\)

Answer 3

`(1+(5-\sqrt{5})/(1-\sqrt{5})).((5+\sqrt{5})/(1+\sqrt{5})+1)`

`=[1-(\sqrt{5}(\sqrt{5}-1))/(\sqrt{5}-1)].[(\sqrt{5}(\sqrt{5}+1))/(1+\sqrt{5})+1]`

`=(1-\sqrt{5})(1+\sqrt{5})`

`=1-5`

`=-4`