Arithmetic Sequence Analysis: Identifying the Term-to-Term Rule

Question

What is the term-to-term rule of the sequence below?

4, 5, 6, 7, ...

Video Solution

Solution Steps

00:00 Find the sequence formula
00:04 Identify the first term according to the given data
00:10 Note the constant difference between terms
00:14 This is the constant difference
00:24 Use the formula to describe an arithmetic sequence
00:30 Substitute appropriate values and solve to find the sequence formula
00:52 Properly expand brackets, multiply by each factor
00:59 Continue solving
01:05 And this is the solution to the question

Step-by-Step Solution

To determine the term-to-term rule for the sequence 4,5,6,7,4, 5, 6, 7, \ldots, we should follow these steps:

  • Step 1: Identify the difference between consecutive terms.
  • Step 2: Establish the rule based on the constant difference.

Let's proceed with the solution:

Step 1: First, notice the differences between consecutive terms in the sequence: 54=1,65=1,76=1 5 - 4 = 1, \quad 6 - 5 = 1, \quad 7 - 6 = 1

It is clear that each term increases by 1.

Step 2: Since each term increases by 1, the term-to-term rule is to add 1 to the previous term. Therefore, if we denote the nn-th term by TnT_n, then the subsequent term Tn+1T_{n+1} can be described by: Tn+1=Tn+1 T_{n+1} = T_n + 1

This term-to-term rule can also be expressed in terms of the sequence starting point: Tn=n+3 T_n = n + 3 where nn is the term position in the sequence starting from the first term being termed T1=4T_1 = 4. Hence, choice 1 (n+3)(n+3) correctly represents each term in the sequence starting from n=1n = 1.

Therefore, the term-to-term rule for the sequence is Tn=n+3T_n = n + 3.

Answer

n+3 n+3