Machine-translated by Google. Questions are authored in English.
Top

Discussion

The solution of the differential equation \(\frac{d^{2}y}{dt^{2}} - y\) = 0, subject to the boundary conditions y(0) = 1, \(y(\infty)\) = 0 is :

  • A.cos t + sin t
  • B.cosh t + sinh t
  • C.cos t - sin t
  • D.cosh t - sinh t

Answer: D

The solution is cosh t - sinh t.

The equation \(y'' - y = 0\) has the general solution \(y = Ae^{t} + Be^{-t}\). The condition \(y(\infty) = 0\) forces \(A = 0\), and \(y(0) = 1\) gives \(B = 1\), so \(y = e^{-t}\).

Since \(\cosh t - \sinh t = e^{-t}\), the answer is cosh t - sinh t. The option cosh t + sinh t equals \(e^{t}\), which grows without bound, and the trigonometric options solve \(y'' + y = 0\), a different equation.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.