Question

Answer 1

\(=\left(1-2\sqrt{2}+3\sqrt{2}\right)\left(\sqrt{2}-1\right)=\left(\sqrt{2}+1\right)\left(\sqrt{2}-1\right)=1\)

Answer 2

VT $= (1 - 3\sqrt2 + 4\sqrt2)\sqrt{2 - 2\sqrt2 +1} = (1 + \sqrt2).\sqrt{(\sqrt2 - 1)^2} = (1+\sqrt2).|\sqrt2-1| = (\sqrt2+1).(\sqrt2-1) = 2-1=1 =$ VP.

Ta có ĐPCM.