SOLUTION: Let A be a nonsingular matrix. If the set {X1,X2,X3} is linearly independent, then the set {AX1,AX2,AX3} is also linearly independent

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Question 1026822: Let A be a nonsingular matrix. If the set {X1,X2,X3} is linearly independent, then the set {AX1,AX2,AX3} is also linearly independent
Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
{ X%5B1%5D,X%5B2%5D,X%5B3%5D} a linearly independent set means that the equation
c%5B1%5DX%5B1%5D+%2B+c%5B2%5DX%5B2%5D+%2B+c%5B3%5DX%5B3%5D+=+0,
will be true only if c%5B1%5D, c%5B2%5D, c%5B3%5D are all equal to 0.
(The 0 on the right side is the zero column vector.)
==> A%28c%5B1%5DX%5B1%5D+%2B+c%5B2%5DX%5B2%5D+%2B+c%5B3%5DX%5B3%5D%29+=+A%2A0
==> c%5B1%5DAX%5B1%5D+%2B+c%5B2%5DAX%5B2%5D+%2B+c%5B3%5DAX%5B3%5D+=+0
In view of the fact that (i) there is no possibility for any of the AX%5Bk%5D vectors to become zero vectors or to be linear combinations of the other vectors because A is nonsingular, and (ii) the only possible values for the c constants are still 0, we conclude that { AX%5B1%5D,AX%5B2%5D,AX%5B3%5D} is still a linearly independent set.