Problem 4 - Algebra and Trigonometry Real Mathematics, Real People

Question

Is 4 or 1 the common difference of the arithmetic sequence \(a_{n}=4 n+1 ?\)

Step-by-Step Solution

Answer

The common difference of the arithmetic sequence \(a_{n}=4 n+1\) is 4.

Step 1: Identify the Given Values

In the given equation \(a_{n}=4 n+1\), \(4n\) is multiplied by n, which means 4 is the part of the definition of the arithmetic sequence. The 1 at the end of the equation is a constant and not multiplied by n, thus it can't be the common difference.

Step 2: Compare with Arithmetic Sequence Formula

The arithmetic sequence equation is of the form \(a_{n}= kd + c\). Here, the expression multiplying n (i.e., 'k') is the common difference. Compare this with the given equation \(a_{n}=4 n+1\), it's seen that 4 is in the place of the common difference (d).

Step 3: Conclude the Common Difference

By comparing and deducing from the given arithmetic sequence, it is determined that the common difference for the sequence \(a_{n}=4 n+1\) is 4, not 1. Thus, 4 is the correct answer.

Key Concepts

Understanding Common Difference in Arithmetic Sequences

In arithmetic sequences, the term "common difference" refers to a consistent value that separates one term from the next. This is key as it defines the sequence's behavior. When looking at an arithmetic sequence, each term after the first is produced by adding the common difference to the preceding term. For example, if the first term is 3 and the common difference is 2, the sequence becomes: 3, 5, 7, 9, and so on. If you have the expression for a sequence such as \(a_n = 4n + 1\), identifying the common difference involves focusing on the coefficient of \(n\). In this scenario, it's the number 4. This coefficient tells us how much we are adding to produce successive terms. Remember:

• The common difference is always the coefficient of \(n\) in the formula.
• It is the value consistently "added" to move from one term to the next.

The Role of Sequence Formula in Arithmetic Progressions

To find terms in an arithmetic sequence easily, a sequence formula is used, generally represented as \(a_n = d(n-1) + a_1\). This formula helps you find the \(n\)-th term by using:

• \(d\), the common difference, clearly describes how terms increase or decrease.
• \(a_1\), the first term, is the starting number of your sequence.
• \(n\), the term number you wish to find.

In the specific example given in the exercise, \(a_n = 4n + 1\), our task is simpler because the sequence formula is already structured to show the relationship between the sequence length and the progression of numbers. You can see immediately that 4 is the rate of increase as per the arithmetic sequence characteristics.

The Connection of Algebra in Arithmetic Sequences

Algebra serves as the foundation upon which arithmetic sequences are built. By utilizing algebraic expressions, we can succinctly describe the properties of sequences.The algebraic approach helps clarify relationships between numbers, revealing how they progress in predictable patterns. For the sequence \(a_n = 4n + 1\), algebra provides the toolkit to uncover that the common difference is 4.Some helpful algebraic insights include:

• Algebra allows us to create and manipulate sequence formulas, helping solve for any term in the series.
• Algebraic principles enable the verification of whether a sequence fits the arithmetic nature by confirming the uniformity of the common difference.

By regularly leveraging algebra, you can efficiently navigate and understand more complex sequences and their behaviors.