Question

please tell me the solution ​

Answer 1

Step-by-step explanation:

$= {x}^{2} - {y}^{2} \\ \\ = {( \frac{2 - \sqrt{5} }{2 + \sqrt{5} } )}^{2} - {( \frac{2 + \sqrt{5} }{2 - \sqrt{5} } )}^{2} \\ \\ = ({\frac{2 + \sqrt{5} }{2 - \sqrt{5} } } + { \frac{2 - \sqrt{5} }{2 + \sqrt{5} } )}({ \frac{2 + \sqrt{5} }{2 - \sqrt{5} }} - { \frac{2 - \sqrt{5} }{2 + \sqrt{5} } )} \\ \\ = (\frac{ ({2 + \sqrt{5}) }^{2} + {(2 - \sqrt{5} )}^{2} }{ {2}^{2} - { (\sqrt{5}) }^{2} } ) \times (\frac{ ({2 + \sqrt{5}) }^{2} - {(2 - \sqrt{5} )}^{2} }{ {2}^{2} - { (\sqrt{5}) }^{2} } ) \\ \\ = \frac{18}{4 - 5} \times \frac{8 \sqrt{5} }{4 - 5} \\ \\ = 18 \times 8 \sqrt{5} \\ \\ = 144 \sqrt{5}$

Answer 2

Answer is given in the pic.