answer:
it is general formula that is used to write value to its excet position
a11 a12 a13
a21 a22 a23
it is the example of order 2 by 3 matrix in this
a11 means value occur in 1 st row 1st column
a12 means value occurs in 1st row 2nd column
a13 means value occur in 1st row and 3rd column
a21 means value occurs in 2nd row and 1st column
a22 means value occurs in 2nd row and in 2nd column
a23 means value occurs in 2nd row and in 3rd column