Question

Find the sum of first 12 terms of the following APs: (i) 11, 5, -1,-7....​

Answer 1

Step-by-step explanation:

Here....

a=11

d=-6

to find: S12

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

S12=12/2(2*11+11*-6)

S12=6(22-66)

S12=6*-44

S12=-264

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