solution:
βc= a b , that is product of a and b is possible only when when a is m Γ n matrix and b is n Γ 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 Γ n)matrix
b= (n Γ p)matrix
then a b = [ (m Γ n)matrix] Γ[ (n Γ p)matrix ]
ββc= a b= [m Γ p ] matrix
ββsize of product a b will be equal to = number of rows of a Γ number of columns of b