Which of the following are expressions? Check all that are true.

A. y = 5/b

B. 275

C. 52 = 25

D. x

E. 3(5x + 7)

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

1 mph

step-by-step explanation:

if the question is asking how much does she drive per mile then,

13 / 13 = 1 mph