Chapter 9: Problem 8
Write the first four terms of the sequence. $$a_{n}=-(-5)^{n-1}$$
Short Answer
Expert verified
The first four terms are -1, 5, -25, 125.
Step by step solution
01
Understand the Sequence Formula
The sequence is defined by the formula \(a_n = -(-5)^{n-1}\). This means that for each term \(n\), the term value is \(-1\) times \(-5\) raised to the power \((n-1)\).
02
Calculate the First Term
For the first term, set \(n = 1\). Substitute into the formula: \(a_1 = -(-5)^{1-1} = -(-5)^0 = -1\).
03
Calculate the Second Term
For the second term, set \(n = 2\). Substitute into the formula: \(a_2 = -(-5)^{2-1} = -(-5)^1 = 5\).
04
Calculate the Third Term
For the third term, set \(n = 3\). Substitute into the formula: \(a_3 = -(-5)^{3-1} = -(-5)^2 = -25\).
05
Calculate the Fourth Term
For the fourth term, set \(n = 4\). Substitute into the formula: \(a_4 = -(-5)^{4-1} = -(-5)^3 = 125\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Power Functions
Power functions are an essential part of algebra and pre-calculus. They involve expressions where a variable is raised to a constant power. In simple terms, if you have a function of the form \(f(x) = ax^n\), you have a power function. Here, \(a\) is a constant, \(x\) is the variable, and \(n\) is a non-negative integer.In the original exercise, we see a sequence formula, \(a_n = -(-5)^{n-1}\), including a power function, where \(-5\) is raised to the power of \((n-1)\). This demonstrates how power functions can be part of more complex algebraic expressions beyond simple polynomials. Understanding power functions helps:
- Recognize different types of growth – linear, quadratic, or cubic.
- Solve algebraic equations involving variables raised to a power.
- Analyze behaviors of sequences and series involving powers.
Exponents
Exponents are a shorthand way to represent repeated multiplication of the same factor. For instance, \(5^3\) means multiplying 5 by itself three times: \(5 \times 5 \times 5\). Exponents play a critical role in simplifying expressions and solving equations. They show up everywhere in mathematics and are especially important in sequences and series.In our sequence formula, \(-(-5)^{n-1}\), the exponent \(n-1\) dictates how many times the base \(-5\) is multiplied by itself. One intriguing part of this formula is the negative sign outside of the power expression, indicating that the result is always multiplied by \(-1\). Thus, every calculation respects the rules of exponents:
- \(a^0 = 1\) for any nonzero \(a\).
- \(a^1 = a\).
- \(a^m \times a^n = a^{m+n}\).
- \((a^m)^n = a^{m \cdot n}\).
Algebraic Expressions
Algebraic expressions are combinations of numbers, variables, and operations that define a specific value or set of values. Variables serve as placeholders that can take on various values. In the expression \(a_n = -(-5)^{n-1}\), \(a_n\) is a function depending on the variable \(n\).Breaking this expression apart, we see:
- The base \(-5\) as a constant factor influenced by \(n-1\), the exponent.
- The negative sign leading the expression, flipping the sign of the resulting power.