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CSS Applied Mathematics QUESTION #4148
Question 1
Using variation of parameters for $y'' + y = \sec(x)$, what is the Wronskian $W$ of $y_1 = \cos(x)$ and $y_2 = \sin(x)$?
  • $0$
  • $1$
  • $-1$✔️
  • $\sec^2(x)$
Correct Answer Explanation
$W = \begin{vmatrix} \cos(x) & \sin(x) \ -\sin(x) & \cos(x) \end{vmatrix} = \cos^2(x) + \sin^2(x) = 1$.