Answer
(b) $\alpha'(x)= A(x)\alpha(x).$
Work Step by Step
Since $\alpha(x)=e^{\int P(x)dx}$, then $$\alpha'(x)=P(x)e^{\int P(x)dx}=P(x)\alpha(x).$$
Then the right answer is:
(b) $\alpha'(x)= A(x)\alpha(x).$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.