Question

In an AP 3rd term is 8 and the 9th term is 2 more then the 3types of 3rd term then prove that the sum of 19th term is 551

Answer 1

Given,a+2d=8, a+8d=3(a+2d)+2

a+2d=8,. 2a+2d=2

2d=8-a,. 2a+8-a=2

a= -6

d=14

sum of 19 terms=19/2(2(-6)+18(14))

=19/2(240)=228

Answer 2

hey mate here is the answer for you.
note that Sn= n/2[2a+(n-1)d].
please mark it as brainliest.