Demarco paid $3.19 per gallon both times that he stopped for gas on a weekend trip. he bought 12.53 gallons of gas the first time and 11.86 gallons the second time. which expression shows the total cost in dollars of the gas he bought on this trip?

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