Question

ICBSE SP 20191
(ii) The nth term of an AP is - 49. Its first term and the common difference are
36 and - 5 respectively. Find the sum of n terms of the AP.​

Answer 1

Answer:

last term =-49

a=36 d=-5

an=a+(n-1)d

-49=36+(n-1)×-5

-49-36=(n-1)×-5

-85=(n-1)×-5

-85/-5=n-1

17=n-1

n=18

Sn=a+an=36+(-49)=-13

therefore, sum of n term is -13

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