Question

For an AP, if t_1=22,t_n= (-11) and s_n=66 then find n.





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Answer 1

Answer:

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Answer 2

Answer:

First term=22

nth term=-11

a+(n-1)d=-11

22+(n-1)d=-11

(n-1)d=-11-22

(n-1)d=-33

Sn=n/2[2a+(n-1)d]

66=n/2[2×22+(-33)]

132=n[44-33]

132=n×11

n=132/11

n=12