(Solved): If a \( 4 \times 4 \) matrix \( A \) with rows \( v_{1}, v_{2}, v_{3} \), and \( v_{4} \) has deter ...

If a \( 4 \times 4 \) matrix \( A \) with rows \( v_{1}, v_{2}, v_{3} \), and \( v_{4} \) has determinant \( \operatorname{det} A=-7 \), then \( \operatorname{det}\left[\begin{array}{c}v_{1} \\ 8 v_{2}+4 v_{4} \\ v_{3} \\ 2 v_{2}+9 v_{4}\end{array}\right]= \)