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> If $\{ a\_n\}$ be a sequence of positive real numbers such that $$a\_n=\sqrt{a\_{n-1}a\_{n-2}},n>2$$ then show that the sequence is convergent to $(a\_1a\_2^2)^{1/3}$. 
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How I proceed: Take square of $a\_n$ so I get $a\_n^2=a\_{n-1}a\_{n-2} \implies a\_n^3=a\_na\_{n-1}a\_{n-2}$. Then stuck. Please help.