Răspuns:
Ex. 2. a)
[tex](\frac{x}{\sqrt{2} } -\sqrt{2} )^2-x(\frac{x}{2} -\sqrt{2} )-\sqrt{2} (1-\sqrt{2} )x=\\=(\frac{x\sqrt{2} }{2}-\sqrt{2})^2-\frac{x^2}{2}+x\sqrt{2} -\sqrt{2} (x-x\sqrt{2} )\\=\frac{2x^2}{4}-\frac{4x}{2}+2-\frac{x^2}{2}+x\sqrt{2} -x\sqrt{2} +2x\\=\frac{x^2}{2}-2x+2-\frac{x^2}{2}+2x\\=2[/tex]
b)
[tex]N=E(n)+2*E(n)+1485[/tex]
[tex]=2+2*2+1485 = 4+1487=1491\\1491:7=213 => 1491[/tex]- este divizibil cu 7
