Question

Алгебра восьмой класс

Answer 1

$x=\sqrt{2} +1\\\\x^{2}+3x\sqrt{2} +5=(\sqrt{2}+1)^{2}+3\sqrt{2}\cdot(\sqrt{2} +1)+5=2+2\sqrt{2}+1+6+3\sqrt{2} +5=\\\\=\boxed{14+5\sqrt{2} }$