Which of the following tables does not represent a function? x y
-1 1
-2 1
-3 1

x y
-5 1
-5 -2
-5 -5

x y
-4 0
2 0
5 7

x y
-5 1
-3 -2
-1 -5

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