Given the matrix: [math]\begin{bmatrix} x_{11} & x & x_{13} & \dots & x_ \\ x_{21} & x & x_{23} & \dots & x \\ \hdotsfor{5} \\ x_{d1} & x_{d2} & x_{d3} & \dots & x_{dn} \end{bmatrix}[/math] , What is the answer?
valid question