Question

Il 3rd
A.P
is 18 and 7th term is
terms of
9th teren
find
10​

Answer 1

1. 3rd term of AP is 18
2. it can be written as a8=a+(7-1)d=18
3. a+6d=18........(1)
4. 7th term of AP is = 10 term of the AP
5. 7th term = a+(6-1)d
6. a+5d.......(2)
7. 9th term =a+(8-1)d
8. a+7d.......(3)
9. from 2 and 3
10. 2a+8d=0..........(4)
11. solving 1 and 4
12. a+6d=18.......(1)×2
13. 2a+8d=0........(4)×1
14. 2a+12d=36-2a+8d
15. we get
16. 4d=36

• d=8
• by substitute d=8 In equ 1
• a=-30
• 10th term =a+(9-1)d
• -30+8×8
• -30+64
• +34
• ●{a10=34}