Calculating Wronskian for u and v: f+3g and f-g

  • Thread starter Success
  • Start date
  • Tags
    Wronskian
In summary, the Wronskian of u and v is equal to the Wronskian of f and g, tcos(t)-sin(t), expanded and simplified using properties of determinants.
  • #1
Success
75
0
If the Wronskian of f and g is tcos(t)-sin(t), and if u=f+3g, v=f-g, find the Wronskian of u and v.

W=fg'-gf'
(f+3g)(f-g)'-(f+3g)'(f-g)
What's next?
 
Physics news on Phys.org
  • #2
Do not delete the template when you post. It's there for a reason. I'll let it slide this time...
Success said:
If the Wronskian of f and g is tcos(t)-sin(t), and if u=f+3g, v=f-g, find the Wronskian of u and v.

W=fg'-gf'
(f+3g)(f-g)'-(f+3g)'(f-g)
What's next?
You have fg' - gf' = tcos(t)-sin(t).

I would expand (f+3g)(f-g)'-(f+3g)'(f-g) to see what that does. (f - g)' is just f' - g', and similar for (f + 3g)'.
 
  • #3
It would be easier to use properties of determinants. For example, what is W(u+v,g) in general for any u and v in terms of simpler Wronskians.
 

FAQ: Calculating Wronskian for u and v: f+3g and f-g

What is the Wronskian of u and v?

The Wronskian of u and v, denoted by W(u,v), is a mathematical tool used to determine linear independence and solutions of differential equations. It is defined as the determinant of the matrix [u v u' v'], where u' and v' are the derivatives of u and v, respectively.

How do you calculate the Wronskian for u and v?

To calculate the Wronskian for u and v, we first find the derivatives of u and v. Then, we create a matrix with u, v, u', and v' as its columns. Finally, we take the determinant of this matrix to find W(u,v).

What is the significance of the Wronskian in solving differential equations?

The Wronskian is used to determine if a set of functions, in this case u and v, are linearly independent. If the Wronskian is non-zero, then u and v are linearly independent and can be used as a basis for a solution to a differential equation. If the Wronskian is zero, then u and v are not linearly independent and cannot be used to find a solution.

Can the Wronskian of u and v change over time?

Yes, the Wronskian of u and v can change over time. This is because the derivatives of u and v, which are used to calculate the Wronskian, can change as the functions u and v change. Therefore, the Wronskian is not a constant and can vary with time.

How is the Wronskian used in real world applications?

The Wronskian is used in various fields of science and engineering, such as physics, chemistry, and electrical engineering. It is used to determine the stability of solutions in differential equations, to analyze the behavior of systems, and to solve boundary value problems. It is also used in linear algebra to find eigenvalues and eigenvectors of matrices.

Back
Top