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Mathematics
If the sum of an infinite GP. is S. Now if the first term is multiplied by 3 and common ratio is reduced to its half then the sum of G.P. is still S, then the common ratio of the G.P. is
Q. If the sum of an infinite GP. is S. Now if the first term is multiplied by 3 and common ratio is reduced to its half then the sum of G.P. is still S, then the common ratio of the G.P. is
451
99
Sequences and Series
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A
2
1
B
4
1
C
8
1
D
5
4
Solution:
1
−
r
a
=
S
....(1)
1
−
2
r
3
a
=
S
⇒
2
−
r
6
a
=
S
....(2)
From (1) and (2) we get,
r
=
5
4