How many terms of the sequence -35, -28, -21,..... should be taken so that their sum is zero?
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Answer:number of terms to be taken = 11
Step-by-step explanation:
a=-35,d=7 Sn=0,n=?
0=n/2 [2(-35)+(n-1)7]
7n^2-77n=0
n^2 -11n=0
n[n-11]=0
that implies n=11
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