Question

If A={2 -3 4} B={ 3 2 2} ,X={ 1 2 3} ,Y={ 2 3 4} then AB+XY equals

Answer 1

We can only multiply vectors when number of rows of first matrix = number of columns of second matrix

Matrices multiplication rule

• For two matrices to be multiplied, it is necessary that the number of rows of first matrix is equal to the number of column of second matrix. Otherwise, the multiplication will not be possible.

Example

• A= [2 -3 4] , B=  $\left[\begin{array}{ccc}2\\3\\3\end{array}\right]$

• AB= [2 x3 +(-3)x3+4x3]
• AB= [6-9+12]
• AB= 9

Conclusion

Since, the number of rows and columns of both matrices are unequal, we can not perform the said operation.