Trouble understanding matrix set

[sk1234]

Hello,

I am taking a basic linear algebra class and I am having trouble understanding the concept of a set of matrices.
Here is one example:

$$\begin{pmatrix} 3 & 1\\ 1 & -1\\ \end{pmatrix} \in \{ \begin{pmatrix} 1 & 1\\ 1 & 0\\ \end{pmatrix} , \begin{pmatrix} 0 & 0\\ 1 & 1\\ \end{pmatrix} , \begin{pmatrix} 0 & 2\\ 0 & -1\\ \end{pmatrix} |a, b, c \in \mathbb{R}\}$$
I don't understand how this matrix can belong to this set and I found no explanation for this in the textbook.
Could someone could please explain this or share a link with an explanation? Thanks a lot in advance.

 

[tkhunny]

You're going to have to supply the entire problem statement.

Do you REALLY mean "set", or do you mean "basis"?
What are a, b, and c? Are these scalar parameters defined in the problem statement?

There's only one way to get that 3 in the 1-1 position. Start with that.

 

[sk1234]

I'm really sorry, I made a mistake, the exercise belongs to a chapter that I haven't covered yet and that's why I wasn't getting it. Please delete the post, I will be more careful in the future.