Question

calculand (√7-√2)(√7+√2) obtinem

Answer 1

obtinem √7 la puterea a 2 si este egal cu 7

Answer 2

obtinem 7 - 2 = 5
dar daca vrei demonstratie:

$( \sqrt{7} - \sqrt{2} )( \sqrt{7} + \sqrt{2} )=\sqrt{7} ^{2} + \sqrt{7} \sqrt{2} - \sqrt{2} \sqrt{7} - \sqrt{2} ^{2} = \sqrt{7} ^{2} - \sqrt{2} ^{2}$ = 7 - 2 = 5