Let $F=\left[\begin{array}{cccc}1& 0& -1& 7\\ 4& -1& 7& -9\end{array}\right]($a$)$ Are $F{F}^T$ and $F^{T}F$ defined? Yes, both $F{F}^T$ and $F^{T}F$ are defined. $F{F}^T$ is defined and $F^{T}F$ is not defined. $F{F}^T$ is not defined and $F^{T}F$ is defined. No$,$ both $F{F}^T$ and $F^{T}F$ are not defined. $($b$)$ What size is each product? $($If the matrix is undefined, enter DNE into both answer blanks.$)F{F}^T$ is $$ and $F^{T}F$ is $$