/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 47 Find the sum. $$\sum_{k=1}^{5}... [FREE SOLUTION] | 91Ó°ÊÓ

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Find the sum. $$\sum_{k=1}^{5} 2^{k-1}$$

Short Answer

Expert verified
The sum is 31.

Step by step solution

01

Understanding the Summation Notation

The given exercise asks us to find the sum of the expression \( \sum_{k=1}^{5} 2^{k-1} \). This notation indicates that we need to evaluate \(2^{k-1}\) for each integer value of \(k\) from 1 to 5, and then add all these evaluated terms together.
02

Evaluating Terms of the Sequence

We systematically calculate each term: - When \(k=1\), the term is \(2^{1-1} = 2^{0} = 1\).- When \(k=2\), the term is \(2^{2-1} = 2^{1} = 2\).- When \(k=3\), the term is \(2^{3-1} = 2^{2} = 4\).- When \(k=4\), the term is \(2^{4-1} = 2^{3} = 8\).- When \(k=5\), the term is \(2^{5-1} = 2^{4} = 16\).
03

Adding the Evaluated Terms

Now, we add up all the terms calculated in the previous step:\[1 + 2 + 4 + 8 + 16\]. Carrying out the addition step-by-step: - \(1 + 2 = 3\)- \(3 + 4 = 7\)- \(7 + 8 = 15\)- \(15 + 16 = 31\)
04

Conclusion

The sum of the series \( \sum_{k=1}^{5} 2^{k-1} \) is 31. We have added together all the terms to find the total sum given in the problem.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Evaluating Sequences
Evaluating sequences is a fundamental concept in mathematics where we need to understand how to approach a list of numbers or terms systematically. In the context of our exercise, a sequence is formed by evaluating the expression \( 2^{k-1} \) for different integer values of \( k \) within a specified range. Each time \( k \) changes, the expression produces a different number.

For our specific exercise, we start with \( k = 1 \) and go up to \( k = 5 \), evaluating \( 2^{k-1} \) for each value:
  • For \( k = 1 \), we have \( 2^{1-1} = 2^0 = 1 \).
  • For \( k = 2 \), we find \( 2^{2-1} = 2^1 = 2 \).
  • \( k = 3 \) yields \( 2^{3-1} = 2^2 = 4 \).
  • With \( k = 4 \), the term becomes \( 2^{4-1} = 2^3 = 8 \).
  • Finally, \( k = 5 \) results in \( 2^{5-1} = 2^4 = 16 \).
Understanding this step helps in breaking down the sequence into clear, manageable terms that can then be manipulated or analyzed further.
Power of Two
The sequence we are dealing with in this exercise is constructed using powers of two, which is a common mathematical topic. The expression \( 2^{k-1} \) shows how powers of two originate from a base of 2 raised to a particular exponent.

Powers of two are significant because they frequently appear in various areas, such as computer science, to represent binary numbers or memory storage. In the step-by-step breakdown:
  • \( 2^0 = 1 \) is the start point, denoting a single unit.
  • \( 2^1 = 2 \) allows us to double the previous amount.
  • \( 2^2 = 4 \) continues this pattern by doubling again.
  • Similarly, \( 2^3 = 8 \) and \( 2^4 = 16 \) keep multiplying the previous result by 2.
Recognizing these patterns helps us understand how quickly the values grow in an exponential sequence, providing insight into both the exercise and the fundamental exponential behavior of powers of two.
Adding Series Terms
In mathematics, adding series terms is crucial for determining the total value of a sequence of numbers. Once we have evaluated each term in our sequence, the next step is summing them up, which transforms separate entities into a cumulative total.

For this exercise, after determining that our terms are 1, 2, 4, 8, and 16, we proceed to add them:
  • Adding the first two terms: \( 1 + 2 = 3 \).
  • Then, \( 3 + 4 = 7 \).
  • Next, \( 7 + 8 = 15 \).
  • Finally, combining with the last term, \( 15 + 16 = 31 \).
Each addition step brings us closer to the complete sum of the sequence. This process emphasizes the importance of precision in calculation and showcases the cumulative power of series addition, leading to the final result of 31 in this exercise.

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Most popular questions from this chapter

Determine whether the infinite geometric series is convergent or divergent. If it is convergent, find its sum. $$1+\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\cdots$$

Paying off a Debt Margarita borrows \(\$ 10,000\) from her uncle and agrees to repay it in monthly installments of \(\$ 200\). Her uncle charges \(0.5 \%\) interest per month on the balance. (a) Show that her balance \(A_{n}\) in the \(n\) th month is given recursively by \(A_{0}=10,000\) and $$ A_{n}=1.005 A_{n-1}-200 $$ (b) Find her balance after six months.

Evaluate the expression. $$\left(\begin{array}{l}5 \\\0\end{array}\right)+\left(\begin{array}{l}5 \\\1\end{array}\right)+\left(\begin{array}{l}5 \\ 2\end{array}\right)+\left(\begin{array}{l}5 \\\3\end{array}\right)+\left(\begin{array}{l}5\\\4\end{array}\right)+\left(\begin{array}{l}5 \\\5\end{array}\right)$$

Amortizing a Mortgage When they bought their house, John and Mary took out a \(\$ 90,000\) mortgage at \(9 \%\) interest, repayable monthly over 30 years. Their payment is \(\$ 724.17\) per month (check this, using the formula in the text). The bank gave them an amortization schedule, which is a table showing how much of each payment is interest, how much goes toward the principal, and the remaining principal after each payment. The table below shows the first few entries in the amortization schedule. $$\begin{array}{|c|c|c|c|c|}\hline \begin{array}{c}\text { Payment } \\\\\text { number }\end{array} & \begin{array}{c}\text { Total } \\\\\text { payment }\end{array} & \begin{array}{c}\text { Interest } \\\\\text { payment }\end{array} & \begin{array}{c}\text { Principal } \\\\\text { payment }\end{array} & \begin{array}{c}\text { Remaining } \\\\\text { principal }\end{array} \\\\\hline 1 & 724.17 & 675.00 & 49.17 & 89,950.83 \\\2 & 724.17 & 674.63 & 49.54 & 89,901.29 \\\3 & 724.17 & 674.26 & 49.91 & 89,851.38 \\\4 & 724.17 & 673.89 & 50.28 & 89,801.10 \\\\\hline\end{array}$$ After 10 years they have made 120 payments and are wondering how much they still owe, but they have lost the amortization schedule. (a) How much do John and Mary still owe on their mortgage? [Hint: The remaining balance is the present value of the \(240 \text { remaining payments. }]\) (b) How much of their next payment is interest, and how much goes toward the principal? [Hint: since \(9 \% \div 12=0.75 \%,\) they must pay \(0.75 \%\) of the remaining principal in interest each month.]

Fibonacci's Rabbits Fibonacci posed the following problem: Suppose that rabbits live forever and that every month each pair produces a new pair that becomes productive at age 2 months. If we start with one newborn pair, how many pairs of rabbits will we have in the \(n\) th month? Show that the answer is \(F_{n},\) where \(F_{n}\) is the \(n\) th term of the Fibonacci sequence.

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