Question

poem or the event.
r. Find the sum of first 19 term of an A.P. whose 8th
term is a 41and 13th term is 6l.​

Answer 1

Answer:

a+ 7d = 41

a+ 12d = 61

- - -

- 5d= -20

d= 4

a+ 7*4=41

a + 28 =41

a = 41-28

a= 13

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

Sn = 19/2[2*13 + (19-1).4]

Sn = 19/2 [ 26 + 72]

Sn= 19/2 [ 98]

Sn = 19/2 * 98

Sn =19*49

Sn = 931

hope its help you