If (a_1=6) and (a_{n+1}=a_n+2), what is the value of (a_5-a_3)?
Answer and explanation
Correct answer: 4
The recursive rule increases each term by 2. Thus the terms are 6, 8, 10, 12, 14. Hence \(a_3=10\) and \(a_5=14\), so \(a_5-a_3=14-10=4\). The value 2 is the increase for one step only; there are two steps from \(a_3\) to \(a_5\). Exam tip: when subtracting two terms, count the number of steps between their indices.
Frequently asked questions
What is the correct answer to this question?
4
Why is this the correct answer?
The recursive rule increases each term by 2. Thus the terms are 6, 8, 10, 12, 14. Hence \(a_3=10\) and \(a_5=14\), so \(a_5-a_3=14-10=4\). The value 2 is the increase for one step only; there are two steps from \(a_3\) to \(a_5\). Exam tip: when subtracting two terms, count the number of steps between their indices.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Recursive rule.
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