- #1
a.merchant
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Homework Statement
Let A be a fixed 2x2 matrix. Assuming that the set:
W={X:AX=2X}
has infinitly many solutions, determine whether it is a subspace of M(2,1)
Homework Equations
To determine whether a set is a subspace i need to prove that there is a zero vector, that it is closed under addition and scalar multiplication
The Attempt at a Solution
If A is 2x2 then AX can't be a subspace of a 2x1 space can it? Unless X is 2x1 but without knowing what X is how to I begin to prove that it is a subspace? Please help!