Sequence And Series Flashcards
1
Q
Nth term of an AP
A
a(n)=a+(n-1)d
2
Q
Sum of n terms of an AP?
A
S(n)=n/2 [2a+(n-1)d]
3
Q
Arithmetic mean of n numbers A=?
A
A= a1+a2+……+aN/N
4
Q
Inserting n AM’s between 2 numbers a,A1,A2,….An,b, common difference d=?
A
d= b-a/n+1
5
Q
In arithmetic progression , aN + a’N=?
A
aN+a’N=a+l
; aN and a’N are nth terms of an AP from first and last term respectively
6
Q
a,b,c are 3 consecutive terms of an AP. 2b=?
A
2b= a+ c
7
Q
Tn= nth term of an AP from first term , then Tn=?
A
T(n)=S(n)-S(n-1)
8
Q
Nth term of a GP
A
a(n)=ar^n-1
9
Q
Nth term of a GP from the end
A
a’n=l/r^n-1
10
Q
Sum of n terms of a GP
A
S(n)=a(r^n-1)/r-1
11
Q
Sum of n terms of a GP when last term is known
A
S(n)=a-lr/1-r
12
Q
b,c, and d are three consecutive terms of a GP. c^=?
A
c^=bd
