The third term of an A.P is 8 and 9th term of the A.P.exceeds three times the third term by 2.find the sum of its first 19th terms.

Answer 1

a+2d = 8
a+8d = 3(a+2d)+2 = 26

so, 6d = 18, and d=3

Now you can find a, and answer the question.

Answer 2

a= 2
S19=551

Answer 3

a+2d=8
a+8d=3(a+2d)+2=26
6d=18
d=6
put d in a+2d= 8
a+2(3)=8
a+6=8
a=8-2
a=2
Sn= n/2[2a+(n-1)d]
=n/2[2(2)+(n-1)3]
n/2[4+3n-3]
2n+3n-3
5n+3
n=5/3

Answer 4

how in first 26 came, sir pls..can u explain me....

Answer 5

sir pls can u tell me in first how 26 came...?

Answer 6

how 26 came ??