What is Wronskian: Definition and 87 Discussions

My question will be about item (c). Part (a) Note that for ##x\geq 0## we have ##f(x)=g(x)##. For ##x<0## we have ##f(x)=-g(x)##. Since ##f## is a constant times ##g## then one column of the matrix in the Wronskian is a constant times the other column. Thus, the Wronskian is zero, Note that...

The Wronskian of these two solutions is also a function of ##x##. $$W=y_1y_2'-y_1'y_2$$ $$W'=y_1y_2''+y_1'y_2'-y_1'y_2'-y_1''y_2$$ $$=y_1y_2''-y_1''y_2$$ The two solutions satisfy $$y_1''+Py_1'+Qy_1=0$$ $$y_2''+Py_2'+Qy_2=0$$ Multiply the first by ##y_2## and the second by ##y_1## and...

Looking at the wronskian applications- came across this; Okay, i noted that one can also have this approach(just differentiate directly). Sharing just incase one has more insight. ##-18c \sin 2x -4k\cos x \sin x - 4k\sin x\cos x =0## ##-18c\sin 2x-2k\sin2x-2k\sin 2x=0## ##-18c\sin 2x =...

2000 Convert the differential equation $$\displaystyle y^{\prime\prime} + 5y^\prime + 6y =0$$ ok I presume this means to find a general solution so $$\lambda^2+5\lambda+6=(\lambda+3)(\lambda+2)=0$$ then the roots are $$-3,-2$$ thus solutions $$e^{-3x},e^{-2x}$$ ok I think the Wronskain...

Homework Statement [/B] Homework Equations ##W(x) = C exp (∫ P(x) dx)## ##y''+P(x)y'+g(x)=0## The Attempt at a Solution Divide the origin equation by (x) to get the standard form of the homogeneous equation : ##y'' +\frac{3y'}{x} - \frac{3y}{x}## ##P(x) = \frac{3}{x}## ## exp (- ∫...

Homework Statement Homework Equations The Attempt at a Solution [/B] Is my answer correct ?

Hi PF! I'm solving a differential eigen-value problem in weak form, so I have trial functions. If the Wronskian of trial functions is small but not zero, is linear independence an issue? I have analytic trial functions but am numerically integrating.

Hi PF! I am trying to solve an ODE by casting it as an operator problem, say ##K[y(x)] = \lambda M[y(x)]##, where ##y## is a trial function, ##x## is the independent variable, ##\lambda## is the eigenvalue, and ##K,M## are linear differential operators. For this particular problem, it's easier...

I am trying to show that that the Airy functions defined below satisfy: $W[Ai(x),Bi(x)]=1/\pi$. $$Ai(x)=\frac{1}{\pi} \int_0^\infty \cos(t^3/3+xt)dt$$ $$Bi(x)=\frac{1}{\pi}\int_0^\infty \bigg[ \exp(-t^3/3+xt)+\sin(t^3/3+xt)\bigg]dt $$ I tried to compute it directly but I got stuck, here's the...

Homework Statement Given a set of fundamental solutions {ex*sinx*cosx, ex*cos(2x)} Homework Equations y''+p(x)y'+q(x)=0 det W(y1,y2) =Ce-∫p(x)dx The Attempt at a Solution I took the determinant of the matrix to get e2x[cos(2x)cosxsinx-2sin(2x)sinxcosx-cos(2x)sinxcosx-...

I am confused about determining when two or more functions are linearly independent. My textbook notes that the Wronskian can do this, but then it also mentions the definition of linear Independence, that the linear combination ##c_1 f_1 + c_2 f_2 + ... + c_n f_n = 0## only has the trivial...

Homework Statement If two differentiable functions are linearly dependent on the interval I, then their Wronskian is identically zero on I. Homework EquationsThe Attempt at a Solution We start with the definition of linearly dependence for two functions. ##y_1 = Cy_2## ##\displaystyle...

Homework Statement y''-4y'+4y=(12e^2x)/(x^4) I am trying to solve this differential equation. I know you would use the variation of parameters method, and I am trouble with the wronskian. My solution manual doesn't actually use a wronskian so I can't verify my work Homework EquationsThe...

Homework Statement Solve for the solution of the differential equation and use the method of variation of parameters. x`` - x = (e^t) + t Homework Equations [/B] W= (y2`y1)-(y2y1`) v1 = integral of ( g(t) (y1) ) / W v2 = integral of ( g(t) (y2) ) / W The Attempt at a Solution [/B] yc= c1...

Homework Statement x²y''+xy'+(x²-0,25)y=0 y1= x^-1/2*sin xHomework Equations Abel's equation: W= c.e^-(integrate (p(t))The Attempt at a Solution My Wronskian gave me a first order ODE that I really don't know solve. x^-1/2*sinx y' + (1/2 x^-3/2 sin x- x^-1/2cosx) y2 I don't solved the Abel's...

Homework Statement The problems are in the uploaded file. 18) satisfies the differential equation y''+p(t)*y'+q(t)*y=0 p(t) and q(t) are continuous Homework Equations Wronskian of y1 and y2 The Attempt at a Solution 18) I don't really get this one 19) Solved most but at the end, where I...

In the uploaded file, question 11 says that in b) the solutions y1 and y2 are linearly independent but the Wronskian equals 0. I think it said that they are independent because it's not a fixed constant times the other solution (-1 for -1<=t<=0 and 1 for 0<=t<=1) but it clearly says in the...

Hello! (Wave) Prove that the determinant of the following system $(\star)$ is the Wronskian.$$(\star) \begin{pmatrix} y_1(s) & -y_2(s)\\ -y_1'(s) & y_2'(s) \end{pmatrix} \begin{pmatrix} c_1(s)\\ c_2(s) \end{pmatrix}=\begin{pmatrix} 0\\ \frac{1}{p(s)} \end{pmatrix}$$Hint: Write the equation...

I'm given bases for a solution space \left \{ x,xe^x,x^2e^x \right \}. Clearly these form a basis (are linearly independent). But, unless I've made a mistake, doing the Wronskian on this yields W(x) = x^3e^x. Isn't this Wronskian equal to zero at x = 0? Isn't that a problem for...

Using Abel's thrm, find the wronskian between 2 soltions of the second order, linear ODE: x''+1/sqrt(t^3)x'+t^2x=0 t>0 I think I got the interal of 1/sqrt(t^3) to be 2t/sqrt(t^3) but this is very different to the other examples I've done where a ln is formed to cancel out the e in the formula...

I have just learned the first order system of ODE, i found that the Wronskian in second order ODE is |y1 y2 ; y1' y2'| but in first order system of ODE is the Wronskian is W(two solution), i wonder which ones is the general form? thank you very much

Homework Statement Page 133 Homework Equations n/a The Attempt at a Solution What is the process for rewriting the third column? 2x-3 and be rewritten as 2x, and 2-3cosx can be rewritten as 2. I don't get this.

Homework Statement I've been stuck on this problem for three days now, and I have no clue how to solve it. Construct a linear differential equation of order 2, for which { y_1(x) = sin(x), y_2(x) = xsin(x)} is a set of fundamental solutions on I = (0,\pi) . Homework Equations Wronskian for...

If the Wronskian of a set of equations equals 0 over a particular interval in the functions' domain, is it possible for it be non-zero under another interval? Are there any particular proofs for or against this?

So I know there are a few threads and many websites on this, but I am not finding what I am looking for. To determine whether a set of functions are linearly dependent or independent I understand that the Wronskian can be used, but many example problems state that "clearly by inspection" some...

Given standard ODE $ y'' + P(x)y' + Q(x)y=0 $, use wronskian to show it cannot have 3 independent sltns. Assume a 3rd solution and show W vanishes for all x. so 1st row of W = {$ {y}_{1}, {y}_{2},{y}_{3} $}, 2nd row is 1st derivatives, 3rd row is 2nd derivatives. I can find the determinate...

Homework Statement Hello, I was just looking for a quick tip: If I have three distinct solutions to a second order linear homogeneous d.e, how would I show that the wronskian of (y1,y2,y3)(x)=0? I know how to show the wronskian is not zero for a linearly independent set, but I'm confused...

Homework Statement Find the Wronskian of {e^(x)*cos(sqrt(x)), e^(x)*sin(sqrt(x))}. Homework Equations W(f, g)=fg'-gf' The Attempt at a Solution W(f, g)=(e^(x)*cos(sqrt(x)))(e^(x)*cos(sqrt(x))*1/(2x^1/2))-(e^(x)*sin(sqrt(x)))(-e^(x)*sin(sqrt(x))*1/(2x^1/2)+e^(x)*cos(sqrt(x))) After simplifying...

I'm doing a problem about finding the Wronskian but I want to check my answer if it's right or not. How do I find the Wronskian of that problem on Ti-89 Titanium?

Hi guys! How's it going? OK so I'm like totally stuck and I have no idea how to do this.

Compute the Wronskian and simplify. So the first part was easy a) $y_1 = t^2 + 1$ , $y_2 = 3t^2 + k$ =$6t-2kt$ b) for what values of $k$ are the functions linearly independant so would I just solve for $k$? I'm confused What exactly does linearly independant mean?

Hi pf! If ##y_1## and ##y_2## are homogenous solutions to a (not necessarily homogenous) second order linear ODE, we define the Wronskian as $$\begin{vmatrix} y_1 y_2\\ y'_1 y'_2 \end{vmatrix}$$. This derivation seems to stem from the pair of equations involving ##y_1## and ##y_2## satisfying...

Hi, so I am given this problem: Using the Wronskian, show that 1, x, x^2,..., x^(n-1) for n>1 are linearly independent. The wronskian is not zero for at least one value in the interval so it is linearly independent, I just do not know how to show it properly.Thank you! :D

I was just curious and had a question: why does the Wronskian indicate linear independence if ## W ≠ 0 ## but is linearly dependent if ## W = 0 ##? Is there a proof to help understand the exact operations of the Wronskian and why it conveys these properties based on these results alone? Thank you!

Given an nth order DE, how (intuitively and/or mathematically) does computing the Wronskian to be nonzero for at least one point in the defined interval for the solution to the DE ensure the solution is unique and also a fundamental set of solutions? Also, is it true that if W = 0, it is 0 for...

Homework Statement Solve by variation of parameters: y" + 3y' + 2y = sinex Homework Equations Finding the complimentary yields: yc = c1e-x + c2e-2x The Attempt at a Solution I set up the Wronskians and got: μ1 = ∫e-2xsin(ex)dx μ2 = -∫e-xsin(ex)dx The problem is that I have no idea how to...

Homework Statement W(t) = W(y1, y2) find the Wronskian. Equation for both y1 and y2: 81y'' + 90y' - 11y = 0 y1(0) = 1 y1'(0) = 0 Calculated y1: (1/12)e^(-11/9 t) + (11/12)e^(1/9 t) y2(0) = 0 y2'(0) = 1 Calculated y2: (-3/4)e^(-11/9 t) + (3/4)e^(1/9 t)Homework Equations W(y1, y2) = |y1 y2...

According to [Erdely A,1953; Higher Transcendental Functions, Vol I, Ch. VI.] the confluent hypergeometric equation \frac{d^2}{d x^2} y + \left(c - x \right) \frac{d}{d x} y - a y = 0 has got eight solutions, which are the followings: y_1=M[a,c,x] y_2=x^{1-c}M[a-c+1,2-c,x]...

Can anyone point to a proof for the Wronskian formula: W[v,v*] = v'v* - vv*' = 2iIM(v', v*) Thanks

It seems to me that if a row is able to be zeroed out through Gaussian reduction that the determinate of that matrix would equal zero. Therefore, we know that at least one of equations/vectors that constructed the matrix was formed from the other two rows. That is -- that equation is dependent...

1. Use Abel's Formula to find the Wronskian of two solutions of the given differential equation without solving the equation. x2y" - x(x+2)y' + (t + 2)y = 0 2. Abel's Formula W(y1, y2)(x) = ce-∫p(x)dx3. I put it in the form of y" + p(x)y' + q(x)y = 0 to find my p(x) to use for Abel's...

Hey! :) I need some help at the following exercise: Let v_{1}, v_{2} solutions of the differential equation y''+ay'+by=0 (where a and b real constants)so that \frac{v_{1}}{v_{2}} is not constant.If y=f(x) any solution of the differential equation ,use the identities of the Wronskian to show...

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?

Homework Statement In my book, I'm given that ##\vec{x}_1=\left(\begin{matrix}t^2\\t\end{matrix}\right), \vec{x}_2=\left(\begin{matrix}0\\1+t\end{matrix}\right), \vec{x}_3=\left(\begin{matrix}-t^2\\1\end{matrix}\right)## are solutions. My textbook presents an algebraic way to show that the...

On my DE test, I was asked to determine if two solutions to a DE are fundamental solutions. So I confirmed they were both solutions, and took the Wronskian, which was nonzero. I got points marked off, and he put a minus sign in front of my wronskian result. Isn't the sign of the...

I can't find a reference for what the wronskian formulas are when dealing with a 3rd order D.E. I know that: W= W[y1,y2,y3] W1= 1*W[y2,y3] W2= -1* W[y1,y3] W3= ?

urgent Diff. Eqs. Wronskian question Homework Statement See attached image- it's a lot easier. Homework Equations We know that when the wronskina = 0, it is linearly dependent on most points, and if it is not equal to 0, then the solutions form a fundamental set of solutions because...

I need to show the intervals where the wronskian is linearly independent and linearly dependent.. I don't know how to do that.. Here's what I have:

Here is the question: Here is a link to the question: Differential Equations...Linear independence question? - Yahoo! Answers I have posted a link there to this topic so the OP can find my response.

Homework Statement Is the set $$ \{cos(x), cos(2x)\} $$ linearly independent?Homework Equations Definition: Linear Independence A set of functions is linearly dependent on a ≤ x ≤ b if there exists constants not all zero such that a linear combination of the functions in the set are equal to...