Answer 1

34 + 32 + 30 + ……….. + 10

For this A.P.,

a = 34

d = a₂ − a₁ = 32 − 34 = −2

l = 10

Let 10 be the n^th term of this A.P.

l = a + (n − 1) d

10 = 34 + (n − 1) (−2)

−24 = (n − 1) (−2)

12 = n − 1

n = 13

`S_n = n/2(a+1)`

`=13/2(34+10)`

`=(13xx44)/2 = 13 xx 22`

= 286