Identify the Term-to-Term Rule: Analyzing the 8, 6, 4, 2 Sequence

Question

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

8, 6, 4, 2, ...

Video Solution

Solution Steps

00:00 Find the sequence formula
00:04 Identify the first term according to the given data
00:07 Note the constant difference between terms
00:13 This is the constant difference
00:18 Use the formula to describe an arithmetic sequence
00:24 Substitute appropriate values and solve to find the sequence formula
00:37 Expand brackets correctly, multiply by each factor
00:45 Continue solving
00:50 And this is the solution to the question

Step-by-Step Solution

To solve this problem, we'll approach it step by step:

Step 1: Identify the sequence pattern.
The sequence given is 8, 6, 4, 2, ... Each term is 2 less than the previous one.

Step 2: Determine the common difference.
The difference between any two consecutive terms (e.g., 6 - 8, 4 - 6) is 2 -2 .

Step 3: Use the formula for the nn-th term of an arithmetic sequence.
For a sequence with first term a1=8a_1 = 8 and common difference d=2d = -2, the nn-th term can be calculated using:

an=a1+(n1)d a_n = a_1 + (n-1) \cdot d
This gives us:

an=8+(n1)(2) a_n = 8 + (n-1)(-2)
=82n+2 = 8 - 2n + 2
=2n+10 = -2n + 10

Therefore, the rule for the sequence is an=2n+10 a_n = -2n + 10 .

By comparing this with the given options, the correct choice is:

2n+10 -2n + 10

Answer

2n+10 -2n+10