To apply the rule "rx-axis" to the function \( f(x) = -2x + 1 \), we reflect the function over the x-axis. This transformation changes the sign of the output of the function, which means we replace \( f(x) \) with \( -f(x) \).
Starting with: \[ f(x) = -2x + 1 \]
We reflect it over the x-axis: \[ g(x) = -f(x) = -(-2x + 1) = 2x - 1 \]
Therefore, the correct function \( g(x) \) based on the rule "rx-axis" is: \[ g(x) = 2x - 1 \]
So the answer is: \[ g(x) = 2x - 1 \]