Question

If x=161-72root5 y=161+72root5 xy=?

Answer 1

Hello Mate!

$x = 161 - 72 \sqrt{5} \\ y = 161 + 72 \sqrt{5} \\ xy = (161 - 72 \sqrt{5} )(161 + 72 \sqrt{5} ) \\ {161}^{2} - ( {72}^{2} \times { \sqrt{5} }^{2} ) \\ 25921 - (5184 \times 5) \\ 25921 - 25920 \\ = 1$

Hope it helps☺!