Question

Giúp em đi ạ, em cần gấp lắm!

Answer 1

Đặt \(A=\sqrt{\sqrt{2}-1}-\sqrt{\sqrt{2}+1}\left(A< 0\right)\)

\(\Rightarrow A^2=\sqrt{2}-1+\sqrt{2}+1-2\sqrt{\left(\sqrt{2}-1\right)\left(\sqrt{2}+1\right)}\)

\(\Leftrightarrow A^2=2\sqrt{2}-2\sqrt{2-1}=2\sqrt{2}-2\)

\(\Rightarrow A=-\sqrt{2\sqrt{2}-2}\)(vì \(A< 0\))

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