Brainlag PlusWhen the differences change by the same amount each time, the nth term has an n² term. Find it.
Second differences
- 4, 9, 16, 25, 36, ...
- first differences: 5, 7, 9, 11
- second difference: 2
A constant second difference means a quadratic sequence. The n² coefficient is half the second difference.
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
- Anything you get wrong is saved to your flashcards