If a, b, c and d are in A.P., We need to find out about the terms bcd, acd, abd and abc .

1. Progressions Q20

2. Qn: Progressions
(a) They are also in A.P.
(b) They are also in H.P.
(c) They are also in G.P.
(d) They are not in an A.P., G.P. or H.P.
a, b, c and d are in A.P., What can we say about terms bcd, acd, abd
and abc?

3. Soln: Progressions
a, b, c and d are in A.P.
Dividing through out this A.P. by abcd, we get
a
abcd
,
b
abcd
,
c
abcd
,
d
abcd
are in A.P.
1
bcd
,
1
acd
,
1
abd
,
1
abc
are in A.P.
 bcd, acd, abd and abc are in H.P.
Answer choice (b)
a, b, c and d are in A.P., What can we say about terms bcd, acd, abd
and abc?