Question

if the sum if the first 6 terms of an ap is 36 and that of the first 16 terms is 256 ,find the sum of the first 10 terms?​

Answer 1

Step-by-step explanation:

a+5d= 36.....(i)

a+15d= 256...(ii)

using eq i in eq ii

a+5d+10d = 256

36+10d= 256

10d= 220

d=22

a= 36-110= -74

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

put a & d in this formula and get the sum

Answer 2

Answer:

124

Step-by-step explanation:

S + 16D = 256 --- (i)

S + 6D = 36 --- (ii)

(i) - (ii)

10D = 256 - 36 = 220

=> D = 22

Required,

S + 10D = (S + 6D) + 4D = 36 + 4*22 = 124