Solving a second order ODE using reduction of order

In summary, the conversation involves a person seeking help with an assignment that involves using reduction of order to solve for a second solution to an ode. They are struggling with getting the LHS and RHS to match up and have attached their working for others to review. After a mistake is pointed out in their check, the person realizes their error and thanks the other person for their help.
  • #1
Bonnie
18
1

Homework Statement


Hi there, I have an assignment which involves using reduction of order to solve for a second solution to an ode (the one attached). However this is a method I am new to, and though I have tried several times, I'm somehow getting something wrong because the LHS and RHS are not matching up, that is, when I substitue in the solution I have found, the RHS does not equal zero as it should.

Homework Equations

The Attempt at a Solution


I have attached my working (Sides 1 and 2), if anyone could point out what I'm doing wrong it would be greatly appreciated, this is driving me nuts!
 

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  • s2.jpg
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  • #2
According to wolfram your general solution is correct.

You do a blunt mistake in the check, you put ##y'=-\frac 1 2 t^{-\frac 1 2}##, the minus in front is not needed. It is clear that ##y'=\frac{1}{2} t^{-\frac 1 2}## for ##y=t^{\frac 1 2}##
 
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  • #3
Delta² said:
According to wolfram your general solution is correct.

You do a blunt mistake in the check, you put ##y'=-\frac 1 2 t^{-\frac 1 2}##, the minus in front is not needed. It is clear that ##y'=\frac{1}{2} t^{-\frac 1 2}## for ##y=t^{\frac 1 2}##
Oh, that was dumb. Thank you!
 
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FAQ: Solving a second order ODE using reduction of order

1. What is a second order ODE?

A second order ODE (ordinary differential equation) is a mathematical equation that involves the second derivative of a function. It is commonly used to model physical phenomena in science and engineering.

2. What is reduction of order?

Reduction of order is a technique used to solve second order ODEs by transforming them into first order ODEs. This method involves substituting the second derivative of the function with a new variable, which reduces the order of the equation.

3. When is reduction of order used?

Reduction of order is used when the ODE contains a repeated root or when the general solution of the ODE is known. It is also used when a particular solution is known, but the complementary solution needs to be determined.

4. What are the steps to solve a second order ODE using reduction of order?

The steps to solve a second order ODE using reduction of order are as follows:

  1. Identify the ODE as a second order equation.
  2. Substitute the second derivative with a new variable.
  3. Solve the resulting first order equation for the new variable.
  4. Substitute the value of the new variable back into the original equation.
  5. Solve the resulting first order equation for the original variable.
  6. Combine the complementary and particular solutions to obtain the general solution.

5. What are some applications of solving second order ODEs using reduction of order?

Solving second order ODEs using reduction of order has many applications in science and engineering, such as in modeling the motion of objects under the influence of gravity, analyzing electrical circuits, and studying the behavior of chemical reactions. It is also commonly used in the fields of physics, biology, and economics to describe various phenomena and systems.

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