A un institut, dos de cada tres alumnes fan servir una mascareta reutilitzable i, tres de cada cinc prefereixen portar-ne una d'un sol ús. Quin tipus de mascareta és el més emprat en aquest institut?

solution:

→c= a b , that is product of a and b is possible only when when a is m × n matrix and b is n × p matrix.

that is, number of columns of a= number of rows of b.

so, size of matrix , c= a b is , if a = (m × n)matrix

b= (n × p)matrix

then a b = [ (m × n)matrix] ×[   (n × p)matrix ]

→→c= a b= [m × p ] matrix

→→size of product a b will be equal to = number of rows of a × number of columns of b

the first one, all those points on the line just make a strait line.