1i thought that the the 1st and 2nd terms are both equal to 5 !!!!
but i think you went wrong in the second step....
every term is 3 times the sum of all the terms that follow it
The first two terms of an infinite G. P. are together equal to 5,
and every term is 3 times the sum of all the terms that follow it; find
the series.
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6 Answers
262let gp be --> a,ar,ar2 ,..... ∞
therefore Tn = arn-1 = arn +arn+1 .... ∞
for n=1, T1= ar +ar2 +...∞ = ar1-r =a (first term of series)
therefore 2r=1 or r=1/2;
now from given info- a+ar=5;
or 3a/2=5
a=10/3
hence we can find the series!
1
1in the third step , it is
a = 3ar/1-r
so , r = 1/4
then a =4 and ar = 1 and so on...
6ya i think kunl is rite
coz a + ar = 5
then acc. to quesn
a = ar + ar2 + ar3 .................
a =3 ar / 1-r
so that gives r = 1/4 and a=4...
so the series is 4 , 1 , 1/4................