Question

Ajutatima varog am uitat rezolvarea:
(rad.5-rad.7)inmultit(rad.5+rad.7)=

Answer 1

$a^{2}- b^{2}=(a+b)(a-b)$ si viceversa

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

Answer 2

=rad.5la puterea 2 minus rad.7la puterea 2.         apoi ridicam la putere si scadem coeficientii