I keep getting “Geometric progression” questions wrong in Sequences & Series. What's the trap?
adding the ratio instead of multiplying by it.
The usual trap: adding the ratio instead of multiplying by it. How to avoid it: in a GP you MULTIPLY by r each step, not add. Go back to the definition — a sequence with a constant ratio r; the nth term is a·r^(n−1).
Key point
Geometric progression
Common mistake
adding the ratio instead of multiplying by it.
Memory tip
in a GP you MULTIPLY by r each step, not add.
Tap to watch or see it right here — the app stays open (it only opens a quick search if nothing embeddable is found).