Question is that :
Suppose a matrix $A\in M_n(\mathbb{C})$ is a commutator by which i mean $A=BC-CB$ for some $B,C\in M_n(\mathbb{C})$ then we see that Trace of $A$ is $0$
But Suppose a matrix is of trace zero can we say that it is commutator?
I have tried seeing this for $2\times 2$ matrices and end up with nothing reasonable..
I would be thankful if some one can suggest me a way to proceed in this case.