[tex]a=\sqrt{(\sqrt2-5)^2},\ b=\sqrt{(\sqrt2+5)^2}\\
\text{Are loc proprietatea: }\sqrt {x^2}=|x|,\forall x\in\mathbb{R}\\
a=\sqrt{(\sqrt2-5)^2}=|\sqrt2-5|=5-\sqrt2\\
b=\sqrt{(\sqrt2+5)^2}=|\sqrt2+5|=\sqrt2+5\\
a\cdot b=(5-\sqrt2)(5+\sqrt2)=5^2-\sqrt2^2
=25-2=23[/tex]