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GB-21-05-001 · Geometric sequences

Find the nth term of this geometric sequence.
12,−36,108,−32412,\quad -36,\quad 108,\quad -324

Sequences: Geometric nth Term Supplementary GCSE method — not covered in this booklet
Method
1) Divide consecutive terms to find common ratio r
2) Use nth term = a × r^(n−
1) where a is the 1st term
Worked Example (GB-21-05-001)
1)
Common ratio is -3.
2)
12×(−3)n−112\times(-3)^{n-1}
Ans = 12×(−3)n−112\times(-3)^{n-1}