Question

25. How many terms of the AP.22,20.18.... should be taken so that their sum is zero​

Answer 1

23 Terms should be taken

description:

AP : 22, 20,18

first term : a= 22

second term : a2= 20

common difference : (d) = a2- a1 = 20-22 = -2

now,

let the numbers be n

so, 0= n/2 { 2 X 22 +(n -1) (-2)}

or 0 = n { 44 + 2 -2 n}

or 0 = n { 46 -2n }

or n = 23 .

hence the no is 23