7.\[ \frac{2-i}{3+4i} = ? \] (A)\[ \frac{2-11i}{25} \](B) \[ \frac{-2-11i}{25} \](C)\[ \frac{-2+11i}{25} \](D) \[ \frac{2+11i}{25} \]

16.已知兩矩陣\(A = \begin{bmatrix} 1 & 2 \\ 5 & 7 \end{bmatrix}\) 和 \(B = \begin{bmatrix} -3 & 1 \\ 2 & -2 \end{bmatrix}\) , 則 \(A \times B = \)? (A) -6 (B) 840 (C)\[ \begin{bmatrix} 1 & -3 \\ -1 & -9 \end{bmatrix} \](D)\[ \begin{bmatrix} -3 & 2 \\ 10 & -14 \end{bmatrix} \]