Se foloseste formula de calcul prescurtat [tex]\displaystyle{(a +b)^{2} = a^{2} + 2ab + b^{2} }[/tex]
[tex]\displaystyle{ (1 + \sqrt{2})^{2} = 1^{2} + 2 \cdot 1 \cdot \sqrt{2} + (\sqrt{2})^{2} }[/tex]
[tex]\displaystyle{= 1 + 2\sqrt{2} + 2 = 2\sqrt{2} + 3 }[/tex]
