Odpowiedź :
[tex]x+y=\sqrt{20}\\x-y=\sqrt{18}\\\\x^2-y^2=(x+y)(x-y)\\\\x^2-y^2=\sqrt{18}\cdot\sqrt{20}\\x^2-y^2=3\sqrt{2}\cdot2\sqrt{5}\\x^2-y^2=6\sqrt{10}[/tex]
[tex]x+y=\sqrt{20}\\x-y=\sqrt{18}\\\\x^2-y^2=(x+y)(x-y)\\\\x^2-y^2=\sqrt{18}\cdot\sqrt{20}\\x^2-y^2=3\sqrt{2}\cdot2\sqrt{5}\\x^2-y^2=6\sqrt{10}[/tex]