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AQA GCSE · Question 22.2 · Algebra
A Fibonacci-type sequence begins 5, -9, ...
The sequence is continued by adding the previous two terms.
Work out the next two terms.
A Fibonacci-type sequence begins 5, -9, ...
The sequence is continued by adding the previous two terms.
Work out the next two terms.
How to approach this question
The rule is to add the previous two terms to get the next term.
1. **Find the third term:**
The first two terms are 5 and -9.
Third term = 5 + (-9) = 5 - 9 = -4.
2. **Find the fourth term:**
The previous two terms are now -9 and -4.
Fourth term = -9 + (-4) = -9 - 4 = -13.
The next two terms are -4 and -13.
Full Answer
-4 and -13
A Fibonacci-type sequence generates the next term by summing the two preceding terms.
The sequence starts with: 5, -9
**To find the 3rd term:**
We add the 1st and 2nd terms.
3rd term = 5 + (-9) = 5 - 9 = -4.
The sequence is now: 5, -9, -4
**To find the 4th term:**
We add the 2nd and 3rd terms.
4th term = (-9) + (-4) = -9 - 4 = -13.
The sequence is now: 5, -9, -4, -13
So, the next two terms are -4 and -13.
Common mistakes
✗ Making errors with negative number addition/subtraction.\n✗ Subtracting the terms instead of adding them.
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