Mathematics. Progressions

1. Introduction. 
2. Definition. 
3. General term of an A.P. 
4. Selection of terms in an A.P. 
5. Arithmetic mean. 
6. Properties of A.P. 
7. Definition. 
8. General term of G.P. 
9. Sum of first n terms of a G.P. 
10. Selection of terms in a G.P. 
11. Sum of infinite terms of a G.P. 
12. Geometric mean. 
13. Properties of G.P. 
14. Definition. 
15. General term of an H.P. 
16. Harmonic mean. 
17. Properties of H.P. 
18. nth term of A.G.P. 
19. Sum of A.G.P. 
20. Method of finding sum. 
21. Method of difference. 
22. Special series. 
23. Vn method. 
24. Properties of arithmetic, geometric and harmonic means 
between two given numbers. 
25. Relation between A.P., G.P. and H.P. 
26. Applications of progressions.