Chapter 11: Problem 14
Find all terms of each finite sequence. $$a_{n}=\left(\frac{1}{2}\right)^{3-n}, 1 \leq n \leq 7$$
Short Answer
Expert verified
The terms are \( \frac{1}{4}, \frac{1}{2}, 1, 2, 4, 8, 16 \) for \(n\) from 1 to 7.
Step by step solution
01
- Understand the Sequence Formula
The given sequence formula is \(a_n = \left( \frac{1}{2} \right)^{3-n}\). This formula will be used to find the terms of the sequence for each value of \(n\) from 1 to 7.
02
- Calculate the First Term
For \(n=1\): \[a_1 = \left( \frac{1}{2} \right)^{3-1} = \left( \frac{1}{2} \right)^2 = \frac{1}{4}\]
03
- Calculate the Second Term
For \(n=2\): \[a_2 = \left( \frac{1}{2} \right)^{3-2} = \left( \frac{1}{2} \right)^1 = \frac{1}{2}\]
04
- Calculate the Third Term
For \(n=3\): \[a_3 = \left( \frac{1}{2} \right)^{3-3} = \left( \frac{1}{2} \right)^0 = 1\]
05
- Calculate the Fourth Term
For \(n=4\): \[a_4 = \left( \frac{1}{2} \right)^{3-4} = \left( \frac{1}{2} \right)^{-1} = 2\]
06
- Calculate the Fifth Term
For \(n=5\): \[a_5 = \left( \frac{1}{2} \right)^{3-5} = \left( \frac{1}{2} \right)^{-2} = 4\]
07
- Calculate the Sixth Term
For \(n=6\): \[a_6 = \left( \frac{1}{2} \right)^{3-6} = \left( \frac{1}{2} \right)^{-3} = 8\]
08
- Calculate the Seventh Term
For \(n=7\): \[a_7 = \left( \frac{1}{2} \right)^{3-7} = \left( \frac{1}{2} \right)^{-4} = 16\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
sequence formulas
A sequence formula helps you compute the terms in a sequence by plugging values into the formula. In this problem, the formula provided is: \[a_n = \bigg(\frac{1}{2}\bigg)^{3-n}\]To solve a sequence, you change the value of \(n\) within the given range. Here, the range of \(n\) is from 1 to 7.
- When \(n\) is 1, you substitute 1 into the formula to find the first term.
- Next, changing \(n\) to 2 gives the second term, and so on until you reach the seventh term.
exponents
Exponents represent how many times you multiply a number by itself. In the given sequence, we encounter various exponents on the fraction \(\frac{1}{2}\). Here's a brief explanation of the key points:
- When an exponent is positive, like 2, it means you multiply the base (\(\frac{1}{2}\)) by itself multiple times.
- When an exponent is zero, any non-zero number raised to the power of zero is 1, so \(\bigg(\frac{1}{2}\bigg)^0 = 1\).
- When an exponent is negative, it indicates a reciprocal. For example, \(\bigg(\frac{1}{2}\bigg)^{-2}\) means we take the reciprocal of \(\bigg(\frac{1}{2}\bigg)^2\), which is 4.
term calculations
To find each term in the sequence, you need to substitute different values of \(n\) into the sequence formula and simplify:
- For \(n = 1\): \[a_1 = \bigg(\frac{1}{2}\bigg)^{3-1} = \bigg(\frac{1}{2}\bigg)^2 = \frac{1}{4}\]
- For \(n = 2\):\[a_2 = \bigg(\frac{1}{2}\bigg)^{3-2} = \bigg(\frac{1}{2}\bigg)^1 = \frac{1}{2}\]
- For \(n = 3\):\[a_3 = \bigg(\frac{1}{2}\bigg)^{3-3} = \bigg(\frac{1}{2}\bigg)^0 = 1\]
- For \(n = 4\):\[a_4 = \bigg(\frac{1}{2}\bigg)^{3-4} = \bigg(\frac{1}{2}\bigg)^{-1} = 2\]
- For \(n = 5\):\[a_5 = \bigg(\frac{1}{2}\bigg)^{3-5} = \bigg(\frac{1}{2}\bigg)^{-2} = 4\]
- For \(n = 6\):\[a_6 = \bigg(\frac{1}{2}\bigg)^{3-6} = \bigg(\frac{1}{2}\bigg)^{-3} = 8\]
- For \(n = 7\):\[a_7 = \bigg(\frac{1}{2}\bigg)^{3-7} = \bigg(\frac{1}{2}\bigg)^{-4} = 16\]