Wronskian: Solve "For W(x,fg,fh)=([f(x)]^2)W(g,h)

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In summary, the Wronskian can be used to show that W(x,fg,fh)=([f(x)]^2)W(g,h). The process involves using properties of the determinant and factoring out f from the first row. Additionally, the product rule can be used on the second row and rows can be multiplied and added without changing the determinant. It is important to note that W(x,f(x)*g(x),f(x)*h(x)) must be used on the left side for the equation to work.
  • #1
jaejoon89
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"For the Wronskian, W, Show W(x,fg,fh)=([f(x)]^2)W(g,h)"

How is this done? I know how to use the Wronskian when there's a system of equations, something like y(x) = cosx, y(x)=sinx, y(x)=x, etc. But I'm really clueless about how to proceed here.
 
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  • #2
W(x,fg,fh)=det([[fg,fh],[(fg)',(fh)']]). Right? Now use properties of the determinant. You can factor f out of the first row. Now you have f*det([[g,h],[(fg)',(fh)']]). Use the product rule on the second row. Now you can multiply any row of a determinant by a factor and add it to another row without changing the determinant. Also right? Add -f' times the first row to the second. Getting it yet?
 
  • #3
is that supposed to say W(x,f(g),f(h)) on the left side?
 
  • #4
Alex6200 said:
is that supposed to say W(x,f(g),f(h)) on the left side?

No. It's W(x,f(x)*g(x),f(x)*h(x)). Otherwise it doesn't work.
 

Related to Wronskian: Solve "For W(x,fg,fh)=([f(x)]^2)W(g,h)

1. What is the Wronskian?

The Wronskian is a mathematical tool used to determine the linear independence of a set of functions. It is denoted by W(f1, f2, ..., fn) and is defined as the determinant of a matrix containing the derivatives of the functions.

2. How do you solve for the Wronskian in the given equation?

To solve for the Wronskian in the equation W(x,fg,fh)=([f(x)]^2)W(g,h), you would first need to expand the determinant and then use the product rule to calculate the derivatives of the functions f, g, and h. Once you have the derivatives, you can plug them into the determinant and simplify to solve for the Wronskian.

3. What is the significance of the Wronskian in mathematics?

The Wronskian is an important tool in differential equations, as it helps determine whether a set of solutions to a differential equation are linearly independent. It is also used in the study of linear algebra and linear transformations.

4. Can the Wronskian be used to solve differential equations?

Yes, the Wronskian can be used to solve differential equations. If the Wronskian of a set of solutions to a differential equation is non-zero, then the solutions are linearly independent. This can be used to find a general solution to the differential equation.

5. Are there any other applications of the Wronskian?

Yes, the Wronskian has various applications in physics, engineering, and other fields. It is used in the study of harmonic motion, quantum mechanics, and even in signal processing. It is a versatile tool that has many practical uses in mathematics and other sciences.

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