Question

rút gọn biểu thức : \(\dfrac{5-2\sqrt{5}}{\sqrt{5}}\) - ( \(5\sqrt{5}-3\) ) + \(\sqrt{80}\)

Answer 1

\(\dfrac{5-2\sqrt{5}}{\sqrt{5}}-\left(5\sqrt{5}-3\right)+\sqrt{80}\\ =\dfrac{\sqrt{5}\left(\sqrt{5}-2\right)}{\sqrt{5}}-5\sqrt{5}+3+4\sqrt{5}\\ =\sqrt{5}-2-5\sqrt{5}+3+4\sqrt{5}\\ =\sqrt{5}\left(1-5+4\right)-2+3\\ =0+1\\ =1\)

Answer 2

  

Answer 3

\(=\sqrt{5}-2-5\sqrt{5}+3+4\sqrt{5}=1\)