Hi everyone! So here is the question:

Describe all solutions to Ax = 0 in parametric vector form, where A is row equivalent to the given matrix:

My thoughts so far:

I know that when two matrices are "row equivalent" it means that one of them can be changed to the other by doing row operations. So I assume here, that I can use the matrix in the picture above, insert it where A should be and do row operations on it. If I do that I get the row reduced augmented matrix:

Now, what I find strange here is that, first of all, there seems to be an x_{1}, x_{2}, x_{3}, and x_{4}, but I only have two rows? Somehow I feel like there should have been 4 rows in this matrix, because if I think about it, if this was an equation containing 4 unknowns, I would have to set up 4 simulations equations to solve it. Here I can only set up two which will be:

x_{1}+ 0_{x2}+ 9_{x3}-8_{x4}= 0

0_{x1}+ 1_{x2}-4_{x3}+ 5_{x5}= 0

I feel like this is impossible? I must be doing something wrong here, but I can't figure out what.

Thank you everyone for reading ^_^