You start a chain email and send it to six friends. the next day, each of your friends forwards the email to six people. the process continues for a few days.

Solution:

The following information about the chain email can be Written as follows:

1 Person Email →→6 Persons (E-mail) →6² Persons  (E-mail)→6³ Persons  (E-mail)+.........few Days

As you can see the number of email sent starting from person 1 to 6 persons to 36 persons to 216 persons, forms a Geometric pattern.

So, Sum of the Series = 1 + 6 + 36 + 216 + 1296 +......+  for n days

        =

Formula for n terms of a geometric series

For, Common ratio (r)≥1

Sum of above geometric series up to n terms

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