edited by
6,696 views
3 votes
3 votes

TRUE/FALSE :

1. if V1 and V2 are eigenvectors that correspond to the distinct eigenvalues then they are linearly independent.

2. if V1 and V2 are  linearly independent eigenvectors then they correspond to distinct eigen values.

plz explain or provide some references thanks

edited by

2 Answers

1 votes
1 votes

We can conclude second option with an example,

$\begin{bmatrix} 2 & -2& 1\\ -1& 3& -1\\ 2 & -4 & 3 \end{bmatrix}$

Skipping the calculation step of eigen values. Eigenvalues  are $\lambda1$ = 1,$\lambda2$ = 1,$\lambda3$ = 6,

Eigen Vectors corresponding to eigen value, $\lambda1$ = 1,

Eigen vector you will  get in terms of two linearly independent variable, I have taken k1 and k2 and the vector will be,

(2k1-k2,k1,k2) i.e k1 ( 2,1,0)+k2(-1,0,1)

Now you will see that these two vectors  $\begin{bmatrix} 2\\ 1\\ 0 \end{bmatrix}$ & $\begin{bmatrix} -1\\ 0\\ 1 \end{bmatrix}$  corresponding to one eigen value,$\lambda1 = 1 $.

Both will satisfy the characteristic equation,  $\left ( A-\lambda I \right ) X = 0$

Checking for $\begin{bmatrix} 2\\ 1\\ 0 \end{bmatrix}$ ,

$\begin{bmatrix} 2 -1& -2& 1\\ -1 & 3-1& -1\\ 2 & -4 & 3-1 \end{bmatrix}$ * $\begin{bmatrix} 2\\ 1\\ 0 \end{bmatrix}$

= $\begin{bmatrix} 1& -2& 1\\ -1 & 2& -1\\ 2 & -4 & 2\end{bmatrix}$ * $\begin{bmatrix} 2\\ 1\\ 0 \end{bmatrix}$

= $\begin{bmatrix} 2 * 1 + (-2) * 1+1*0\\ (-1)*2 + 2*1 + (-1)*0\\ 2*2 + (-4)*1 + 2*0 \end{bmatrix}$

= $\begin{bmatrix} 0\\ 0\\ 0 \end{bmatrix}$


Checking for $\begin{bmatrix} -1\\ 0\\ 1 \end{bmatrix}$ ,

$\begin{bmatrix} 2 -1& -2& 1\\ -1 & 3-1& -1\\ 2 & -4 & 3-1 \end{bmatrix}$ * $\begin{bmatrix} -1\\ 0\\ 1 \end{bmatrix}$

= $\begin{bmatrix} 1& -2& 1\\ -1 & 2& -1\\ 2 & -4 & 2\end{bmatrix}$ * $\begin{bmatrix} -1\\ 0\\ 1 \end{bmatrix}$

= $\begin{bmatrix} 1*(-1) + (-2)*0+ 1*1\\ (-1)* (-1) + 2 *0 + (-1 )*1\\ 2* (-1) + (-4) * 0 + 2 *1\end{bmatrix}$

= $\begin{bmatrix} 0\\ 0\\ 0 \end{bmatrix}$


Moreover these vectors are linearly Independent,

C1*$\begin{bmatrix} 2\\ 1\\ 0 \end{bmatrix}$ +C2*  $\begin{bmatrix} -1\\ 0\\ 1 \end{bmatrix}$  =0

The above equation are only possible for C1 = C2 = 0, So both vectors are linearly independent as well.

So its not always the case that if V1 and V2 are two linearly independent eigen vectors then they correspond to distinct eigen values.

0 votes
0 votes
Yes they are linearly independent .

Just have a look at the explanation provided , they have considered the fact initially they are linearly dependent  and then they disproved it .

Condition of linearly dependent vector is :

$C_{1}$ $V_{1}$ + $C_{2}$ $V_{2}$ + $C_{3}$ $V_{3}$  ........... + $C_{n}$ $V_{n}$ = $0$

where some $C_{i}$ $\neq$ $0$ and they are constants , $V_{i}$ are the vectors .

http://math.stackexchange.com/questions/696327/proof-of-eigenvectors-corresponding-to-different-eigenvalues-are-linearly-indep

Related questions

3 votes
3 votes
1 answer
1
4 votes
4 votes
1 answer
2
Prashant Gupta asked Feb 11, 2016
5,827 views
if V1 and V2 are 4-dimensional subspaces of a 6-dimensional vector space V, then the smallest possible dimension of Intersection of V1 and V2 is ?
1 votes
1 votes
0 answers
3
radha gogia asked Nov 1, 2015
425 views
For a 3*3 identity matrix , we have eigen value as 1 but there is no linearly independent vector for it since if they are 3 unknowns then we shall have x=y=z=0 so then ho...