[線代]Row Operations

Row operations on a matrix A can change the linear dependence relations among rows of A

ex

[1 1 1 1] [1 1 1 1]
[2 2 2 2] ~[0 0 0 0]
[1 2 3 4] [0 1 2 3]

原本2 3 列LI 之後變成 LD 所以是 true嗎 ?

另外請問
Let A be m*n matrix with m>n and b be an m*1 vector then Ax=b may have multiple solution
這應該是true吧 ?