Fundamental Solutions of Linear homogeneous equations

In summary, the equation y'' + p(t)y' + q(t)y = 0 with continuous coefficients does not have y = sin(t^2) as a solution on any interval containing t = 0, as when t = 0, the expression on the left side of the equation evaluates to 2. Therefore, y = sin(t^2) cannot satisfy the given differential equation.
  • #1
hsong9
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Homework Statement


Can y = sin(t^2) be a solution on an interval containing t = 0 of an equation y'' + p(t)y' + q(t)y = 0 with continuous coefficients?


Homework Equations





The Attempt at a Solution


y = sin(t^2)
y' = 2tcos(t^2)
y'' = 2cos(t^2) - 4t^2sin(t^2)

2cos(t^2) - 4t^2sin(t^2) + p(t)(2tcos(t^2)) + q(t)sin(t^2) = 0

when t=0, above equation is 2. That is, there does not exist the solution. so y can not be a solution on I containing t=0.
 
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  • #2
hsong9 said:

Homework Statement


Can y = sin(t^2) be a solution on an interval containing t = 0 of an equation y'' + p(t)y' + q(t)y = 0 with continuous coefficients?


Homework Equations





The Attempt at a Solution


y = sin(t^2)
y' = 2tcos(t^2)
y'' = 2cos(t^2) - 4t^2sin(t^2)

2cos(t^2) - 4t^2sin(t^2) + p(t)(2tcos(t^2)) + q(t)sin(t^2) = 0

when t=0, above equation is 2. That is, there does not exist the solution. so y can not be a solution on I containing t=0.

Your reasoning is good, but let me help you with your conclusion. An equation is not a number, so an equation can't be 2.

When t = 0, the value of the expression on the left side of the equation is 2, so y = sin(t^2) cannot be a solution of the differential equation on any interval I containing t = 0.
 
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  • #3
Thanks!
 

1. What is the definition of a fundamental solution of a linear homogeneous equation?

A fundamental solution of a linear homogeneous equation is a set of linearly independent solutions that can be used to express any other solution of the equation. In other words, it is a set of solutions that form a basis for the solution space.

2. How can I determine if a set of solutions is a fundamental solution of a linear homogeneous equation?

A set of solutions is a fundamental solution if they satisfy two conditions: they are linearly independent and they span the solution space. This means that none of the solutions can be written as a linear combination of the others, and any other solution of the equation can be written as a linear combination of the fundamental solutions.

3. Can a linear homogeneous equation have more than one fundamental solution?

Yes, a linear homogeneous equation can have an infinite number of fundamental solutions. In fact, any linear combination of fundamental solutions is also a fundamental solution.

4. How do fundamental solutions relate to the general solution of a linear homogeneous equation?

The general solution of a linear homogeneous equation is a linear combination of the fundamental solutions. This means that by finding the fundamental solutions, we can find the general solution of the equation.

5. What is the significance of fundamental solutions in solving linear homogeneous equations?

Fundamental solutions are important because they provide a way to find the general solution of a linear homogeneous equation. They also help us understand the structure of the solution space and the behavior of the solutions of the equation.

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