Each of the series below shows the first four terms of a geometric series.
Identify the only one of these geometric series that is convergent.
Select the correct answer.
3+6+12+24+…3 + 6 + 12 + 24 + \dots3+6+12+24+…
1−1+1−1+…1 - 1 + 1 - 1 + \dots1−1+1−1+…
81−27+9−3+…81 - 27 + 9 - 3 + \dots81−27+9−3+…
2+4+8+16+…2 + 4 + 8 + 16 + \dots2+4+8+16+…
308 exam-style questions on OCR A Level Maths 1.4 Sequences and Series, covering 1.4.1 Binomial expansion for positive integer n, 1.4.2 Link to binomial probabilities, 1.4.3 Binomial expansion for rational n (A-level only), 1.4.4 Validity of the expansion (A-level only), 1.4.5 Sequences (A-level only), 1.4.6 Increasing, decreasing and periodic sequences (A-level only), 1.4.7 Sigma notation (A-level only), 1.4.8 Arithmetic sequences and series (A-level only), 1.4.9 Geometric sequences and series (A-level only), 1.4.10 Sum to infinity of a geometric series (A-level only), and 1.4.11 Modelling with sequences and series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.