[tex]a = \sqrt{3-2\sqrt2} -\sqrt{3+2\sqrt2}+2\\ \\ a = \sqrt{(\sqrt2-1)^2} -\sqrt{(\sqrt2+1)^2} +2\\ \\ a = \big|\sqrt2-1\big| - \big|\sqrt2+1\big|+2 \\ \\ a = \sqrt2-1-(\sqrt2+1)+2 \\ \\ a = \sqrt2-1-\sqrt2-1+2 \\ \\ a = -2+2 \\ \\ a = 0 \in \mathbb_{N}
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