- #1
NewtonianAlch
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Homework Statement
Find the kernel of the matrix:
[PLAIN]http://img256.imageshack.us/img256/9015/53369959.jpg
The Attempt at a Solution
So I row-reduce it and get:
[PLAIN]http://img812.imageshack.us/img812/1391/97980793.jpg
The system of equations the row-reduced form equals 0.
So I set x[itex]_{3}[/itex] and x[itex]_{4}[/itex] as the free variables and solve for x[itex]_{2}[/itex]: x[itex]_{2}[/itex] = -x[itex]_{3}[/itex] - x[itex]_{4}[/itex]
Substitute that into the top equation to get x[itex]_{1}[/itex] -4(x[itex]_{3}[/itex]+x[itex]_{4}[/itex]) +2x[itex]_{3}[/itex] +7x[itex]_{4}[/itex] = 0
Solve for x[itex]_{1}[/itex]: x[itex]_{1}[/itex] = 2x[itex]_{3}[/itex] - 3x[itex]_{4}[/itex]
From this we get:
Vector(2x[itex]_{3}[/itex]-3x[itex]_{4}[/itex], -x[itex]_{3}[/itex]-x[itex]_{4}[/itex], x[itex]_{3}[/itex], x[itex]_{4}[/itex])
So ker(A) = x = x[itex]_{3}[/itex](2,-1,1,0) + x[itex]_{4}[/itex](-3,-1,0,1)
What does this mean essentially? I know how to solve it, but I don't really understand what I'm doing or what this is useful for. As far as I understand, the kernel is a subspace of a linear map, so what does this translate to in practical terms?
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