Question

How many terms of the A. P. 18 ,16,14,......be Taken so that their sum is zero?

Answer 1

Answer:

Step-by-step explanation:

a=18, d= -2

Sn = 0

n=?

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

n/2(2×18+(n-1)(-2)) = 0

n/2(36-2n+2) = 0

n/2(-2n+38) = 0

n/2×2(-n+19)=0

n(19-n)=0

n=19

Answer 2

a=18 ,d=-2

Sn=0
n/2(2a+(n-1)d)=0
n/2(2(18)+(n-1)-2)=0
n/2(36-2n+2)=0
n/2(-2n+40)=0
-2n^2+40n=0
2n^2=40n
2n=40
n=20

HOPE it helps you