Question

What is the rank of matrix [1 -2 0 2; -1 0 1 3; 1 -1 0 2; 2 -4 1 1]

Answer 1

Row reduce the matrix.
Since all pivots are non-zero, the rank of the matrix is 4.

Answer 2

I got that it's 3

Answer 3

I have the echolon form as
1,-2,0,2
0,1,0,0
0,0,1,5
0,0,0,1
What does yours look like?

Answer 4

it's ok, it's 4... It seems I was working with some other matrix, mistake in rewriting :) thanks

Answer 5

You're welcome!