system of equations and matrice

Question

Which term in the following matrix is ?

Answer 1

Entries in a matrix are classified by row and column respectively and indicated by the subscripts.

For example, a₃₂ represents the entry found in the 3rd row, 2nd column. In your matrix, that indicates 13.

Answer 2

The subscript ₁₁ means first (top) row, first (left) column.

a₁₁ = 3