Rewrite $4$ as $2^2$ to find $4^x=2^{2x}$.  Since $2^8=2^{2x}$, we have $2x=8$ which implies $x=\boxed{4}$.
Question:
If $2^8=4^x$, what is the value of $x$?
Answer:
Let's think step by step.

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4
If $2^8=4^x$, what is the value of $x$?
test