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Ajutati-ma cu exercitiul 5

Răspuns :

[tex] \frac{ \sqrt{5} }{(2- \sqrt{5} )}+ \frac{2}{(2+ \sqrt{5}) }= -\frac{5}{ (\sqrt{5} -2)} + \frac{2}{(2+ \sqrt{5} )} = \\ - \frac{ \sqrt{5} (2+ \sqrt{5}) }{( \sqrt{5}-2)(2+\sqrt{5}) } + \frac{2( \sqrt{5}-2) }{(2+ \sqrt{5})( \sqrt{5}-2)} =- \sqrt{5}(2+ \sqrt{5})+2( \sqrt{5}-2)= \\ -5-2 \sqrt{5} +2 \sqrt{5}-4=-5-4=-9 [/tex]