Brainlag PlusSequences that multiply by the same number each time, growth and decay, and surd ratios.
Multiply by the same number
3, 6, 12, 24, ... multiplies by 2 each time: the common ratio is 2.
Find it by dividing a term by the one before: 24 ÷ 12 = 2.
The ratio can be a fraction (64, 32, 16, ... has ratio 1/2), negative (2, −6, 18, ...) or a surd (1, √2, 2, 2√2, ...).
The nth term is (first term) × ratioⁿ⁻¹, so the 10th term of 3, 6, 12, ... is 3 × 2⁹ = 1536.
The rest of this lesson and its 7 practice questions are in Plus.
Screen 1 of 2, free to read.
- 7 exam-style questions, marked as you go, each with a worked solution
- The Graphing Calculator beside every question
- Anything you get wrong is saved to your flashcards