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karnten07
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[SOLVED] linear algebra - matrix equations
Consider the matrix A =
1 1 1
2 1 0
1 0 -1
a.)
Show that the equation Ax =
1
2
3
has no solutions in R^3, where R is the set of real numbers.
b.) Find two linearly independant vectors b in R^3 such that the equations Ax=b has a solution in R^3.
For part a.) i inserted a vector x of the form
a
b
c
into the equation and then multiplied this x by A. I then had 3 equations in a b and c:
(1) a + b + c = 1
(2) 2a + b =2
(3) a - c = 3
Rearranging (3) i get c = a - 3 and substituting this into (1), it becomes 2a + b = 4
But this contradicts (2) so i conclude that the equation has no solution in R^3.
I am stuck on part b.), if i change the original vector(1,2,3) to b equalling (x,y,z) i can simply replace the terms in the original set of euqations.
In doing this i find that 2a+b=x+z meaning that y = x+z
Is this the right way to do this, and how do i find the numbers in vector b? Could i use x = 1, y=3 and z=2 as one vecotr b as this satisfies my equations? The other being the same numbers but each is negative?
Any help is greatly appreciated, thanks
Homework Statement
Consider the matrix A =
1 1 1
2 1 0
1 0 -1
a.)
Show that the equation Ax =
1
2
3
has no solutions in R^3, where R is the set of real numbers.
b.) Find two linearly independant vectors b in R^3 such that the equations Ax=b has a solution in R^3.
Homework Equations
The Attempt at a Solution
For part a.) i inserted a vector x of the form
a
b
c
into the equation and then multiplied this x by A. I then had 3 equations in a b and c:
(1) a + b + c = 1
(2) 2a + b =2
(3) a - c = 3
Rearranging (3) i get c = a - 3 and substituting this into (1), it becomes 2a + b = 4
But this contradicts (2) so i conclude that the equation has no solution in R^3.
I am stuck on part b.), if i change the original vector(1,2,3) to b equalling (x,y,z) i can simply replace the terms in the original set of euqations.
In doing this i find that 2a+b=x+z meaning that y = x+z
Is this the right way to do this, and how do i find the numbers in vector b? Could i use x = 1, y=3 and z=2 as one vecotr b as this satisfies my equations? The other being the same numbers but each is negative?
Any help is greatly appreciated, thanks