IIT-JEE
Exam
Consider an infinite geometric series with the first term a and common ratio r. If its sum is 4 and the second term is 3/4 then (a,r) has the value,
(a). (7/4,3/7)
(b). (2,3/8)
(c). (3/2,1/2)
(d). (3,1/4)
Read Solution (Total 4)
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- we know that sum of infinite series is a/(1-r)..here sum is given as 4
in GP if first term is a then 2nd term will be ar
given that ar=3/4 & a/(1-r)=4 after solving both eqtn we will get a=3 and r=1/4
so answer d (3,1/4)is correct - 11 years agoHelpfull: Yes(1) No(0)
- given a/1-r=4 & ar=3/4
after solving for r, r=3/4 & 1/4
corresponding values of a are 1 & 3
-1 - 11 years agoHelpfull: Yes(1) No(0)
- for an infinite g.p.... r must be
- 11 years agoHelpfull: Yes(0) No(1)
- (d) option is correct
- 8 years agoHelpfull: Yes(0) No(0)
IIT-JEE Other Question
suppose a,b,c are in AP and a^2, b^2, c^2 are in GP. If a
Which of the following pieces of data does not uniquely determine an acute angled triangle ABC(R=circumradius)?
(a). a,sinA,sinB
(b). a,b,c
(c). a,sinB,R
(d). a,sinA,R