Tính :
a) \( \frac{5}{{ \sqrt 5 - 1}} - \frac{5}{{ \sqrt 5 + 1}}; \) b) \( \sqrt {{{ \left( { \sqrt 5 - 3} \right)}^2}} - \sqrt { \frac{1}{5}} \)
A.\(\begin{array}{l}{\rm{a)}}\,\,\frac{1}{2}\\{\rm{b)}}\,\,\frac{{15 + 3\sqrt 5 }}{5}\end{array}\)
B.\(\begin{array}{l}{\rm{a)}}\,\,\frac{3}{2}\\{\rm{b)}}\,\,\frac{{15 - 3\sqrt 5 }}{5}\end{array}\)
C.\(\begin{array}{l}{\rm{a)}}\,\,\frac{5}{2}\\{\rm{b)}}\,\,\frac{{15 - 6\sqrt 5 }}{5}\end{array}\)
D.\(\begin{array}{l}{\rm{a)}}\,\,2\\{\rm{b)}}\,\,\frac{{15 + 6\sqrt 5 }}{5}\end{array}\)
a) \( \frac{5}{{ \sqrt 5 - 1}} - \frac{5}{{ \sqrt 5 + 1}}; \) b) \( \sqrt {{{ \left( { \sqrt 5 - 3} \right)}^2}} - \sqrt { \frac{1}{5}} \)
A.\(\begin{array}{l}{\rm{a)}}\,\,\frac{1}{2}\\{\rm{b)}}\,\,\frac{{15 + 3\sqrt 5 }}{5}\end{array}\)
B.\(\begin{array}{l}{\rm{a)}}\,\,\frac{3}{2}\\{\rm{b)}}\,\,\frac{{15 - 3\sqrt 5 }}{5}\end{array}\)
C.\(\begin{array}{l}{\rm{a)}}\,\,\frac{5}{2}\\{\rm{b)}}\,\,\frac{{15 - 6\sqrt 5 }}{5}\end{array}\)
D.\(\begin{array}{l}{\rm{a)}}\,\,2\\{\rm{b)}}\,\,\frac{{15 + 6\sqrt 5 }}{5}\end{array}\)
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