What is the Basis for the Subspace V in R3 with the Equation x+2y+3z=0?

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SUMMARY

The basis for the subspace V in R3 defined by the equation x + 2y + 3z = 0 consists of two linearly independent vectors: (-2, 1, 0) and (-3, 0, 1). The initial suggestion of using the matrix [1 0 0; 0 2 0; 0 0 3] is incorrect, as it implies three basis vectors, which would span all of R3 rather than the plane defined by the equation. To find the basis, one must solve for one variable in terms of the others, leading to the identification of the two vectors that span the plane.

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gunnar
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Hi. I need to find a base for the subspace V in R3 which has the equation
x+2y+3z=0
Can someone please tell my if the space I'm looking for is

[1 0 0;0 2 0;0 0 3] ?

If not, please explain what I'm doing wrong
 
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The subspace is a plane. Find two linearly independent vectors lying in the plane.
 
Your answer can't be correct because it has 3 basis vectors and so would span all of R3.
You have one equation is 3 unknowns. Solve for ONE of the unknowns and use the other two as parameters.
x+ 2y+ 3z= 0 so x= -2y- 3z. If you take y= 1, z= 0, then x= -2. One basis vector is (-2, 1, 0). If you take y= 0, z= 1, then x= -3. Another basis vector is (-3, 0, 1).
The basis is [(-2, 1, 0), (-3, 0, 1)].

Of course, a basis is not unique. There are many possible solutions (but they will all contain 2 basis vectors).
 

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