Find a basis for the solution set of the given homogeneous linear system 3 x 1 </ms

Theresa Archer

Theresa Archer

Answered question

2022-06-22

Find a basis for the solution set of the given homogeneous linear system
3 x 1 + x 2 + x 3 = 0
6 x 1 + 2 x 2 + 2 x 3 = 0
9 x 1 3 x 2 3 x 3 = 0
I do what I know I need to do. First I get the solution set of the system by reducing like this:
( 3 1 1 6 2 2 9 3 3 ) ( 3 1 1 0 0 0 0 0 0 ) ( 1 1 / 3 1 / 3 0 0 0 0 0 0 )
So I know x = [ x 1 x 2 x 3 ] = [ 1 1 3 r 1 3 s r s ]
That being the general solution.
Now, giving the values for r and s according to the standard vectors i, j
x = [ x 1 x 2 x 3 ] = [ 1 1 3 r 1 3 s r s ] = r [ 2 3 1 0 ] + s [ 2 3 0 1 ]
From my results, the basis will be:
( [ 2 3 1 0 ] , [ 2 3 0 1 ] )
But instead, the book answer
( [ 1 3 0 ] , [ 1 0 3 ] )
Any idea on what I'm doing wrong?

Answer & Explanation

laure6237ma

laure6237ma

Beginner2022-06-23Added 27 answers

Check your expression for x . It should be
x = [ x 1 x 2 x 3 ] = [ 1 3 r 1 3 s r s ] = r [ 1 3 1 0 ] + s [ 1 3 0 1 ]
Layla Velazquez

Layla Velazquez

Beginner2022-06-24Added 11 answers

don't follow this step.
x = [ x 1 x 2 x 3 ] = [ 1 1 3 r 1 3 s r s ] = r [ 2 3 1 0 ] + s [ 2 3 0 1 ]
Wouldn't you want to write this as:
x = [ x 1 x 2 x 3 ] = [ 1 1 3 r 1 3 s r s ] = r [ 1 3 1 0 ] + s [ 1 3 0 1 ]
If you write out the eigenvalues, you get λ = 1 , 0 , 0
The corresponding eigenvectors are:
( 1 , 0 , 0 ) , ( 1 / 3 , 0 , 1 ) , ( 1 / 3 , 1 , 0 ) and these should look familiar to your solution.

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