If matrix , write AAT.

We are given that,


We need to compute AAT.


We know that the transpose of a matrix is a new matrix whose rows are the columns of the original.


So, transpose of matrix A will be given as



Multiplying A by AT,



In multiplication of matrices,



Dot multiply the matching members of 1st row of first matrix and 1st column of second matrix and then sum up.


(a11 a12 a13)(b11 b21 b31) = a11 × b11 + a12 × b21 + a13 × b31


So,


(1 2 3)(1 2 3) = 1 × 1 + 2 × 2 + 3 × 3


(1 2 3)(1 2 3) = 1 + 4 + 9


(1 2 3)(1 2 3) = 14


Thus,



1