[tex]a=\sqrt{2} -1\\b=\sqrt{2}+1\\ \\a)\ a \times b=(\sqrt{2} -1)(\sqrt{2}+1)=\sqrt{2}^{2}-1^{2}=2-1=1\ \\Precizare:\ din\ formula\ (a-b)(a+b)=a^{2}-b^{2}\\ \\a^{2}+b^{2}=(\sqrt{2} -1)^{2}+ (\sqrt{2} +1)^{2}=(\sqrt{2}^{2}-2\sqrt{2}+1)+(\sqrt{2}^{2}+2\sqrt{2}+1)=8+2=10\\ Precizare:\ formulele\ (a-b)^{2} \ si \ (a+b)^{2}\\\\b) Media \ aritmetica: \ \frac{a + b}{2}=\frac{\sqrt{2}-1+\sqrt{2}+1}{2}=\frac{2\sqrt{2}}{2}=\sqrt{2}\\ \\[/tex]
[tex]Media \ geomtrica: \ \frac{a \times b}{2}=\frac{(\sqrt{2}-1)(\sqrt{2}+1)}{2}=\frac{1}{2}[/tex]
