Question

Find the sum of first 22 terms of the AP 8,3, -2….…​

Answer 1

to find S22

given a=8 ,d=-5

Answer 2

Answer:

Your answer starts from here :

8,3,......

Here, a = 8 , d = 3-8 = -5 and n = 22

We know that :

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

Therefore,

S₂₂ = 22/2 { 16 + 21 ( - 5 ) }

S₂₂ = 11 ( 16 - 105 )

S₂₂ = 11 ( - 89 )

S₂₂ = - 979

Hence, the sum of first 22 terms of the AP is - 979.