I’ve got a confusion. We know a 1x3 row matrix is a 3-vector i.e. x= [ a b c] Matrix x can be written in vector notation like x= a i + b j + c k where i, j, k are unit vectors along x,y & z axes. For dot product of x.x = a2 + b2 + c2 when x= a i + b j + c k But according to the matrix multiplication rule, multiplication of two matrices is possible only when column of 1st matrix = row of the 2nd matrix. So x.x = [ a b c] [ a b c] is not possible My questions are : (1) Both x= [ a b c] and x= a i + b j + c k are same vector. Then why this discrepancy happens? (2) Does really x.x exist when x = [ a b c]? Can we approach in any other way to define x.x when x = [ a b c] ? I’m novice at linear algebra. So it would be helpful for me if you can explain elaborately. I’m really at a loss about that confusion.