Multiplication Of  Matrices
 
Lesson 1
 

Two matrices A and B are conformable for the product AB if the number of columns in A (pre-multiplier) is same as the number of rows in B (post-multiplier).

                                                                               

Let A=[a1 a2 … an] be a row matrix and B be a column matrix B= [ b1, b2, b3……..bn]

 

Then the product of row and column matrix is defined as AB=a1b1+a2b2+...+anbn
 
Problem:                   Multiply:
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Step 1:

(AB)11=(First row of A)(First column of B)
 
4x3 + 4x4 = 12 + 16 = 28  
 
Step 2:

(AB)12=(Second row of A)(First column of B)
 
3x3 + 2x4 = 9 + 8 = 17
 
Step 3: 
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Try two practice problems:
 
Multiply the following:
 
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