Question

The 11th term and 21st term of an A.P.are 16 and 29 respectively then find 31 term of an A.P​

Answer 1

Step-by-step explanation:

1. a11-16
2. a+10d=16--equation1
3. a21-29
4. a+20d=29---equation
5. subtracting 1 and 2
6. a+10d=16
7. -a-+21d=-21
8. =-11d=-15
9. d=15/11
10. putd=15/11 in 1
11. a+110/15=16
12. 15a+110=240
13. 15a=240-110
14. a=130/15=26/3
15. a31=26/3+30(15/11)
16. =26/3+450/11
17. 286+135/33
18. =421/33