If a,d and Sn are first term, common difference and sum of first nth terms of se

If a,d and Sn are first term, common difference and sum of first nth terms of series, then Sb =

n/2[2a+(n-1)d]

n/2[a+(n-1)d]

n/[2a+(n-1)d]

a+(n-1)d

Answer : A

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1) If A, G, H are arithmetic, geometric and harmonic means between a and b respectively, then A,G,H are

2) Sum of n terms of G.P is

n/2[2a+(n-1)d]

a(1-rn)/(1-r)

2ab/(a+b)

a+b/2

3) If a = 3, r = 2, then nth term of G.P is

2.3n-1

3.2n

3.2n+1

3.2n-1

4) 5th term of G.P 3,6,12,… is

15

48

2

3

5) G1,G2,…,Gn are said to be n geometric means between a and b if a,G1,…Gn,b is

a sequence

not a sequence

G.P

A.P