Question

In an AP if a= -15 and tn=1 and Sn= -63 then n is

Answer 1

Answer:

n=9 is the answer.

Step-by-step explanation:

given that, a=-15,Tn=1,Sn=-63

Tn=a+(n-1)d

1=-15+(n-1)d

16=(n-1)d.............eq1

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

-63=n/2(2*-15+16)

-63=n/2(-30+16)

-63=n/2* -14

-63=n*-7

n=-63/-7

n=9

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Answer 2

Here, n = 9.

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