If
the sum of first n terms of A.P is cn^{2}, then the sum of squares of
these n terms is:
(a)n(4n^{2}1)c^{2}/6
(b) n(4n^{2}+1)c^{2}/3
(c) n(4n^{2}1)c^{2}/3 (d) n(4n^{2}+1)c^{2}/6
Solution
follows here:
H


G


A

B

O

C

D

E


F

ColumnI

ColumnII

(a) The number of permutations containing the word ENDEA is

(p) 5!

(b)
The number of permutations in which the letter E occurs in the first and the
last positions is

(q) 2*5!

(C) The number of
permutations in which none of the letters D,L,N occurs in the last five
positions is

(r) 7*5!

(d)
The number of permutations in which the letters A,E,O occur only in odd
positions is

(s) 21*5!
