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Algebra Difficulty 4.7 AIME Find the answer

Let N=2(22)N=2^{(2^{2})} and xx be a real number such that N(NN)=2(2x)N^{(N^{N})}=2^{(2^{x})}. Find xx.

A number or a short expression. Spacing and $ signs are ignored.

Solution

We compute N(NN)=161616=242424=2226+2=2266N^{(N^{N})}=16^{16^{16}}=2^{4 \cdot 2^{4 \cdot 2^{4}}}=2^{2^{2^{6}+2}}=2^{2^{66}} so x=66x=66.

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