Posts

Showing posts with the label Wronskian

Show that the following pair of functions are linearly independent yet Wronskian vanishes on the given interval

Linear Independence and Wronskian Show that the following pair of functions are linearly independent yet their Wronskian vanishes on the given interval $$f_{1}=\begin{cases}x^{2},x\ge0\\ 0,x Sol. The given functions are $$f_{1}=\begin{cases}x^{2},x\ge0\\ 0,x We want to prove that $$f_{1}$$, $$f_{2}$$ are L.I. For this purpose, we shall show that ...(1) if $$c_{1}f_{1}+c_{2}f_{2}=0$$ for all $$x\in\mathbb{R}$$, then each of $$c_{1}$$, $$c_{2}$$ is zero. For this purpose, we use $$x=-1.1$$. Now $$f_{1}(1)=1$$, $$f_{2}(1)=0$$, and $$f_{1}(-1)=0$$, $$f_{2}(-1)=1$$. Substituting these values in (1), we get, $$c_{1}\cdot1+c_{2}\cdot0=0\Rightarrow c_{1}=0$$ and $$c_{1}\cdot0+c_{2}\cdot1=0\Rightarrow c_{2}\rightarrow0$$ We have $$c_{1}f_{1}+c_{2}f_{2}=0\Rightarrow c_{1\frac{3}{3}}=c_{2}=0$$ Hence $$f_{1}$$, $$f_{2}$$ are linearly independent on the given interval. Now, we find the Wronskian of the given functions. Two cases arise. Case I. When $$x\...

Show by Wronskian that x, x^3, x^4 are Linearly Independent if x is non-zero.

Image
  Let          f1(x) = x,     f2(x) = x^3,     f3(x) = x^4                  f'1(x) = 1,    f'2(x) = 3x^2  f'(x) = 4x^3                  f"1(x) = 0,   f"2(x) = 6x,    f"3(x) = 12x^2 W( f 1, f 2, f 3) =                     =  Taking x common form 1st Row                =                =  Now,                                         = x(24x^4 - 18x^4)                                        = 6x^5 which is not equal to o Therefore...

Prove that if the Wronskian of the functions are Linearly Independent over I

Image
Th. Prove that if the Wronskian of the functions \(f_{1}\, f_{2}\, \ldots f_{n}\) over an Interval I is non-zero, then the functions are linearly independent over I. Proof Proof: Consider the relation \[ c_{1}f_{1} + c_{2}f_{2} + \ldots + c_{n}f_{n} = 0 ...(1)\] where \( z_{1}, c_{2}, \ldots, c_{n} \) are constants. Differentiating (1) successively \( n-1 \) times with respect to \( x \), we get, \[ c_{1}f'_{1} +c_{2}f'_{2} +c_{3}f'_{3} + \ldots + c_{n} {f_{n}}^{\prime} = 0 ...(2)\] \[ c_{1}f''_{1} + c_{2}f''_{2} + \ldots + c_{n}f''_n = 0 ...(3)\] \[ c_{1}{f_{1}}^{(n-1)} + c_{2}{f_{2}}^{(n-1)} + \ldots + c_{n}{f_{n}}^{(n-1)} = 0 ...(n)\] Here The Vidoe in Youtube These \( n \) equations can be written as \[ \begin{bmatrix} f_{1} & f_{2} & \ldots & f_{n} \\ f'_{1} & f'_{2} & \ldots & f'_{n} \\ f"_{1} & f"_...