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Consider the equation $y''-5y'+9y=0$. Suppose $y_1, y_2$ are two solutions and the corresponding Wronskian at $x=0$ is $5$.

Then, the Wronskian of them at $x=5$ by Abel's formula is:

$5e^{25}$

$5e^{-25}$

$5e^{-45}$

$5e^{45}$