Laplace transform IVP 2nd order

In summary, the conversation discusses finding the solution to y''+6y'+10y=0, with initial conditions y(0)=2 and y'(0)=1. The solution involves taking the Laplace transform and isolating for Y(s), then splitting it into two terms and using inverse Laplace to find the final solution. There is a discrepancy between the given solution and the expected solution, with the mistake possibly being in replacing s with s+3.
  • #1
Pi Face
76
0

Homework Statement



y''+6'+10y=0
y(0)=2
y'(0)=1

Homework Equations





The Attempt at a Solution



Laplace everything and I get
s^2*Y(s)-2s-1+6s*Y(s)-12+10Y(s)=0

isolate Y(s)
Y(s)=(2s+13)/(s^2+6s+10)

split into 2 terms, bottom can be rearranged by completing the square

2s/[(s+3)^2+1^1] + 13/[(s+3)^2+1^1]

inverse laplace

y(t)=2e^-3t*cost + 13e^-3t*sint

both wolfram and the answer key say the last term should be 7 instead of 13, but i don't see where I made a mistake
 
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  • #2
[tex]L^{-1}\frac s{(s+b)^2+a^2}=e^{-bx}(\cos ax-\frac ba\sin ax)[/tex]
 
  • #3
The Laplace transform of ##\cos t## is ##\frac{s}{s^2+1}##, so when you replace s by s+3, you get ##\frac{s+3}{(s+3)^2+1}##. Compare that to what you said was the Laplace transform of ##e^{-3t}\cos t##.
 

FAQ: Laplace transform IVP 2nd order

What is a Laplace transform IVP 2nd order?

A Laplace transform IVP 2nd order is a mathematical technique used to solve second-order differential equations, which are equations that involve the second derivative of a function. It transforms the original differential equation into an algebraic equation, making it easier to solve.

How is a Laplace transform IVP 2nd order used?

A Laplace transform IVP 2nd order is used to solve differential equations in engineering, physics, and other fields of science. It is especially useful for solving problems involving vibrations, electrical circuits, and heat transfer.

What are the steps for solving a Laplace transform IVP 2nd order?

The steps for solving a Laplace transform IVP 2nd order are as follows:

  1. Transform the differential equation into an algebraic equation using the Laplace transform.
  2. Solve the algebraic equation for the transformed function.
  3. Apply the inverse Laplace transform to find the solution in the original function.
  4. Use initial conditions to determine the constants in the solution.

What are the advantages of using a Laplace transform IVP 2nd order?

The advantages of using a Laplace transform IVP 2nd order include:

  • It can solve a wide range of differential equations, including those with discontinuous or piecewise functions.
  • It simplifies the solution process by transforming the problem into an algebraic equation.
  • It can handle initial value problems, which involve finding the solution at a specific point in time.
  • It has applications in various fields of science and engineering.

What are some common mistakes to avoid when using a Laplace transform IVP 2nd order?

Some common mistakes to avoid when using a Laplace transform IVP 2nd order are:

  • Not properly transforming the differential equation into an algebraic equation.
  • Forgetting to apply the inverse Laplace transform to find the solution in the original function.
  • Incorrectly handling initial conditions.
  • Using the wrong Laplace transform table.
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