Each term of the Fibonacci sequence is the sum of the two preceding terms. If the eighth term is 21 and the ninth is 34, what is the tenth term?

1. The Fibonacci rule defines each term from the two that come before it. 2. So the tenth term is the ninth term plus the eighth term. 3. That is 34 + 21 = 55. 4. Doubling the ninth term would give 68 and adding 13 would give 47, but neither uses the two immediately preceding terms. _Source: OpenStax Algebra and Trigonometry (CC BY 4.0), Ch 13 "Sequences, Probability and Counting Theory", section 13.1 Sequences and Their Notations_