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Question 1 - Think & Reflect (Page 184) - Sum of the First n Natural Numbers - Chapter 8 - Predicting What Comes Next: Exploring Sequences & Progress
Last updated at June 9, 2026 by Teachoo
Class 9
Chapter 8 - Predicting What Comes Next: Exploring Sequences & Progress
- Definition
- Explicit Rule for a Sequence
- Recursive Rule for a Sequence
- Virahānka–Fibonacci sequence
- Exercise Set 8.1
- Arithmetic Progressions
- Visualising an AP
-
Sum of the First n Natural Numbers
- Exercise Set 8.2
- Geometric Progressions
- Fractals as a GP Sequence
- Visualising a GP
- Exercise Set 8.3
- End-of-Chapter Exercises
Transcript
Question 1 - Think & Reflect (Page 184) Can the same approach be used to find the sum of 1 + 2 + 3 + … + 100? Yes, we can use the same approach S = 1 + 2 + 3 + 4 + 5 + …… + 99 + 100 S = 100 + 99 + 98 + 97 + 96 + …… + 2 + 1 Adding both equations S + S = 101 + 101 + 101….. 100 times 2S = 101 × 100 S = 𝟏/𝟐 × 101 × 100 S = 101 × 50 S = 5050
