Chapter 14: Problem 6
$$ \begin{aligned} &a_{n}=2 n^{2}-6 \\ &-4,2,12,26,44 \end{aligned} $$
Short Answer
Expert verified
The given sequence matches the formula \(a_n = 2n^2 - 6\).
Step by step solution
01
Understanding the Sequence Formula
The sequence is given by the formula \( a_n = 2n^2 - 6 \). This formula tells us that for any term \( a_n \), we need to substitute the value of \( n \) into the formula to find the corresponding sequence term.
02
Substituting Values to Find Terms
Let's find the terms for \( n = 1, 2, 3, 4, \) and \( 5 \): - For \( n = 1 \), \( a_1 = 2(1)^2 - 6 = 2 - 6 = -4 \).- For \( n = 2 \), \( a_2 = 2(2)^2 - 6 = 8 - 6 = 2 \).- For \( n = 3 \), \( a_3 = 2(3)^2 - 6 = 18 - 6 = 12 \).- For \( n = 4 \), \( a_4 = 2(4)^2 - 6 = 32 - 6 = 26 \).- For \( n = 5 \), \( a_5 = 2(5)^2 - 6 = 50 - 6 = 44 \).
03
Comparing with Given Sequence
The terms we calculated \(-4, 2, 12, 26, 44\) match the sequence given in the problem \(-4, 2, 12, 26, 44\). Therefore, the formula is verified to generate the sequence.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Sequence Formula
A sequence formula is a mathematical expression defining the rule for generating the terms of a sequence. In the given exercise, the sequence is defined by the formula \( a_n = 2n^2 - 6 \). This indicates that the sequence follows a quadratic pattern.Here’s how a sequence formula works:
- Each term in the sequence is the result of applying the formula with a particular value of \( n \), the term's position in the sequence.
- The sequence starts at \( n = 1 \) and continues with consecutive natural numbers \( n = 2, 3, 4, \ldots \).
- The formula assists in predicting any term of the sequence without directly counting each preceding term.
Term Calculation
In mathematics, calculating each term of a sequence involves evaluating the sequence formula for specific values of \( n \). Let's discuss how term calculation works for the problem at hand.Using the formula \( a_n = 2n^2 - 6 \):
- Identify the position \( n \) of the term you want to calculate. For example, \( n = 3 \) corresponds to the third term.
- Substitute the value of \( n \) into the formula: for \( n = 3 \), compute \( a_3 = 2(3)^2 - 6 \).
- Perform the arithmetic operations: calculate \( 2(3)^2 = 2 \times 9 = 18 \), then subtract 6 to get 12. Hence, the third term \( a_3 \) is 12.
Substitution Method
The substitution method is a simple yet powerful technique used in sequences for calculating terms. It involves replacing variables in a formula with specific numerical values.Here's how substitution is applied:
- Identify the sequence formula, which in our case is \( a_n = 2n^2 - 6 \).
- Select the value of \( n \), which represents the term position you are interested in. For instance, to find the fourth term choose \( n = 4 \).
- Substitute \( n \) with the chosen value in the formula: \( a_4 = 2(4)^2 - 6 \).
- Evaluate the arithmetic expressions: \( 2(4)^2 = 2 \times 16 = 32 \), and then subtract 6 leading to \( 32 - 6 = 26 \).