Cue Column:

• What types of progressions are tested?
• Which formulas are non-negotiable?
• How to approach unknown series?

Note Column: JEE Main tests 4 progression types: AP, GP, AGP, and HP, plus special summation series. The core approach is: (1) identify the progression type from the given terms or conditions, (2) apply the correct nth term and sum formulas, (3) for non-standard series, decompose the general term into summable parts (partial fractions, telescoping, or known sums). The most tested formulas are $S_n$ for AP, $S_n$ and $S_{inf}$ for GP, sum(k), sum($k^2$), sum($k^3$), and the AGP technique (S - rS). AM-GM-HM inequality appears in optimization problems.

Summary: Identify progression type -> apply formula -> for non-standard series, decompose general term. AM-GM-HM for optimization.