4
<|im_start|>system
You are a helpful assistant.<|im_end|>
<|im_start|>user
If $4:x^2 = x:16$, what is the value of $x$?
Please reason step by step, and put your final answer within \boxed{{}}.<|im_end|>
<|im_start|>assistant

user
4
If $4:x^2 = x:16$, what is the value of $x$?
train