Question

the 4th term of AP is equal to 3 times the first term and 7th term excess which the third term by 1. find its nth term​

Answer 1

Answer:

a4=3×a1 =a+3d=3a

3d=2a-------1 eq.

a7-a3=1

a+6d-a+2d=1

a+8d=1 --------2 eq.

from 1

d=2a/3

put in 2

a+8×2a/3=1

a+16a/3=1

3a+16a=3

19a=3

a=3/19----3 eq put in 1

d=2×3/19/3

d=38

a9=3/19×8×38