Expression : $$x=\frac{1}{\sqrt{2}+1}$$
=> $$x=\frac{1}{\sqrt{2}+1} \times \frac{\sqrt{2}-1}{\sqrt{2}-1}$$
=> $$x=\frac{\sqrt{2}-1}{(\sqrt{2})^2-(1)^2} = \frac{\sqrt{2}-1}{2-1}$$
=> $$x=\sqrt{2}-1$$
To find : $$x^2+2x-1$$
= $$(\sqrt{2}-1)^2+2(\sqrt{2}-1)-1$$
= $$(2+1-2\sqrt{2})+(2\sqrt{2}-2)-1$$
= $$3-3=0$$
=> Ans - (C)
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