Question

the sum of a certain number of terms of an ap series -8,-6,-4....is 52. the number of terms is​

Answer 1

Step-by-step explanation:

Given: Sn=52, a=-8, d=a2-a1=-6-(-8)=-6+8=2.

To find= n=?

Formula: Sn=n/2(2a+(n-1)d)

52(2)=n(2(-8)+(n-1)2)

104=-16n+2n²-2n

104=-18n+2n²

2n²-18n-104=0

2n²-26n+8n-104=0

2n(n-13)+8(n-13)=0

(2n+8)(n-13)

n=-8/2

Hence, n=13

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Answer 2

Answer:

answer attached in photo