źródło:
-x+6=0
-x=-6
x=6
D=R-{6}
(x\sqrt{2}+2x\sqrt{8})^2=(x\sqrt{2})^2+2*x\sqrt{2}*2x\sqrt{8}+(2x\sqrt{8})^2=2x^2+4x^2\sqrt{16}+32x^2*=2x^2+4*4x^2+32x^2=50x^2
(a+b)^2=a^2+2ab+b^2 (\sqrt{a})^2=a \sqrt{a}*\sqrt{b}=\sqrt{ab}