If sum of n terms of ARTHEMATIC PROGRESSIONS 2,5,8 is 155 then the number of terms is
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Difference=5-2= 3
sum of n terms=n/2(2a+(n-1)d)
Given:- Sn= 155, a= 2, d= 3, n=?
155=n/2(4+3n-3)
155= n/2(1+3n)
n= 155×2-1/3
n= 103
sum of n terms=n/2(2a+(n-1)d)
Given:- Sn= 155, a= 2, d= 3, n=?
155=n/2(4+3n-3)
155= n/2(1+3n)
n= 155×2-1/3
n= 103
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