Answers

2014-10-07T06:59:28+05:30
Arithmetic progression:-
last term an = a+(n-1)d
sum to n terms = n/2 (2a+(n-1)d) or
                       = n/2(a+l)
common ratio r = a₂/a₁
geometric progression:-
last term = a(r) power n-1
sum to n terms =  a(r power n-1/r-1) r>1
                           ar r=1
                           a (1-r power n/ 1-r) r<1
1 3 1
2014-10-07T09:24:40+05:30
Arithmetic progression:-
tn=a+(n-10)d
n=a+b÷2
Sn=n÷2(2a+n-1×d)or
Sn=n÷2(a+l)

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