How many terms of ap 18,16,14 taken so that there sum is 0.

1.	How many terms of ap 18,16,14 taken so that there sum is 0.
Answer» As Sn=1/2(2a+(n-1)d) So, 0=1/2(2(18)+(n-1)(-2)) 0=36+(n-1)(-2) -36=(n-1)(-2) -36/-2=(n-1) 18=n-1 18+1=n n=19

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