Maths Olympiad Prep

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Algebra Difficulty 4.2 AIME Find the answer

Let xx be a real number such that 2x=32^{x}=3. Determine the value of 43x+24^{3 x+2}.

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

Solution

We have 43x+2=43x42=(22)3x16=26x16=(2x)616=3616=116644^{3 x+2}=4^{3 x} \cdot 4^{2}=\left(2^{2}\right)^{3 x} \cdot 16=2^{6 x} \cdot 16=\left(2^{x}\right)^{6} \cdot 16=3^{6} \cdot 16=11664

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