Lesson eLearning

The numbers are generated by the rule: next number = 2 × previous number – 3. Starting with 5, what is the 4th number in the sequence?

medium 2 marks Class 1 · Mathematics · Patterns
Answer
19

The correct answer is 19 — Thus the 4th number is 19.

Step-by-step solution

  1. Set the first term (a_1=5).
  2. Compute the second term: (a_2=2\times5-3=7).
  3. Compute the third term: (a_3=2\times7-3=11).
  4. Compute the fourth term: (a_4=2\times11-3=19).
  5. Thus the 4th number is 19.
Common mistake: Misapplying the recurrence or forgetting to subtract 3

Concept tested: Recurrence relation in patterns

Published · How this solution was prepared and checked

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