Mathematics with Applications, Books a la Carte, and MyLab Math with Pearson eText - Title-Specific Access Card Package (12th Edition)
12th Edition
ISBN: 9780134862651
Author: Lial
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
Chapter 6.1, Problem 1CP
Checkpoint1
Use the substitution method tosolve this system:
Answers to Checkpoint exercises arefound at the end of the section.
Expert Solution & Answer
Learn your wayIncludes step-by-step video
schedule04:02
Students have asked these similar questions
search
P(QP) Q
1.-P:PR
2.-QP:PR
3.
Q:MT 1, 2
4. Q:DNE 3
Submit
4.5
P. (QP) Q
1. P: PR
2.
Q-P PR
3. -Q:AS
4. -P:MP 2, 3
5.
Submit
17
A
Previous Chapter Next Chapter
1. Find the area of the region enclosed between the curves y = x and y = x.
Sketch the region.
for the given rectangular coordinates, find two sets of polar coordinates for which 0≤θ<2π, one with r>0 and the other with r<0. (-2sqrt(3),9)
Chapter 6 Solutions
Mathematics with Applications, Books a la Carte, and MyLab Math with Pearson eText - Title-Specific Access Card Package (12th Edition)
Ch. 6.1 - Checkpoint1 Use the substitution method tosolve...Ch. 6.1 - Checkpoint 2
Use the elimination method to solve...Ch. 6.1 - Checkpoint 3
Solve the system of equations .
Draw...Ch. 6.1 - Checkpoint 4
Solve the following system:
Ch. 6.1 - Checkpoint 5
Solve the system
Draw the graph of...Ch. 6.1 - Prob. 6CPCh. 6.1 - Prob. 1ECh. 6.1 - Prob. 2ECh. 6.1 - Use substitution to solve each system. (See...Ch. 6.1 - Use substitution to solve each system. (See...
Ch. 6.1 - Use substitution to solve each system. (See...Ch. 6.1 - Use substitution to solve each system. (See...Ch. 6.1 - Use elimination to solve each system. (See...Ch. 6.1 - Use elimination to solve each system. (See...Ch. 6.1 - Use elimination to solve each system. (See...Ch. 6.1 - Use elimination to solve each system. (See...Ch. 6.1 - Use elimination to solve each system. (See...Ch. 6.1 - Prob. 12ECh. 6.1 - Prob. 13ECh. 6.1 - Use elimination to solve each system. (See...Ch. 6.1 - Use elimination to solve each system. (See...Ch. 6.1 - Prob. 16ECh. 6.1 - In Exercises 17 and 18, multiply both sides of...Ch. 6.1 - In Exercises 17 and 18, multiply both sides of...Ch. 6.1 - Millennials The number of baby boomers has been...Ch. 6.1 - Prob. 20ECh. 6.1 - Slow Midwestern Growth According to US. Census...Ch. 6.1 - Booming Florida At the start of the millennium,...Ch. 6.1 - Google Trends According to Google Trends, popular...Ch. 6.1 -
24. Heart Disease and Cancer Deaths The number of...Ch. 6.1 - Workforce Participation for Women and Men On the...Ch. 6.1 - Prob. 26ECh. 6.1 - Theater Tickets A 200-seat theater charges $8 for...Ch. 6.1 - Prob. 28ECh. 6.1 - Prob. 29ECh. 6.1 - Prob. 30ECh. 6.1 - Prob. 31ECh. 6.1 - Prob. 32ECh. 6.2 - Checkpoint 1
Use the elimination method to solve...Ch. 6.2 - Prob. 2CPCh. 6.2 - Checkpoint 3 Perform the given row operations on...Ch. 6.2 - Prob. 4CPCh. 6.2 - Prob. 5CPCh. 6.2 - Prob. 6CPCh. 6.2 - Prob. 7CPCh. 6.2 - Checkpoint 8
Solve each system.
(a)
(b)
Ch. 6.2 - Prob. 9CPCh. 6.2 - Prob. 1ECh. 6.2 - Prob. 2ECh. 6.2 - Prob. 3ECh. 6.2 - Prob. 4ECh. 6.2 - Prob. 5ECh. 6.2 - Prob. 6ECh. 6.2 - Obtain an equivalent system by performing the...Ch. 6.2 - Obtain an equivalent system by performing the...Ch. 6.2 - Obtain an equivalent system by performing the...Ch. 6.2 - Prob. 10ECh. 6.2 - Prob. 11ECh. 6.2 - Obtain an equivalent system by performing the...Ch. 6.2 - Prob. 13ECh. 6.2 - Write the augmented matrix of each of the given...Ch. 6.2 - Prob. 15ECh. 6.2 - Prob. 16ECh. 6.2 - Prob. 17ECh. 6.2 - Prob. 18ECh. 6.2 - Prob. 22ECh. 6.2 - Prob. 21ECh. 6.2 - Use the indicated row operation to transform each...Ch. 6.2 - Prob. 20ECh. 6.2 - In Exercises 21-24, the reduced row echelon form...Ch. 6.2 - In Exercises 21-24, the reduced row echelon form...Ch. 6.2 - In Exercises 21-24, the reduced row echelon form...Ch. 6.2 - In Exercises 21-24, the reduced row echelon form...Ch. 6.2 - Prob. 25ECh. 6.2 - Prob. 28ECh. 6.2 - In Exercises 25-30, perform row operations on the...Ch. 6.2 - In Exercises 25-30, perform row operations on the...Ch. 6.2 - In Exercises 25-30, perform row operations on the...Ch. 6.2 - Prob. 32ECh. 6.2 - Prob. 33ECh. 6.2 - Prob. 34ECh. 6.2 - Write the augmented matrix of the system and use...Ch. 6.2 - Write the augmented matrix of the system and use...Ch. 6.2 - Write the augmented matrix of the system and use...Ch. 6.2 - Write the augmented matrix of the system and use...Ch. 6.2 - Write the augmented matrix of the system and use...Ch. 6.2 - Prob. 40ECh. 6.2 - Prob. 41ECh. 6.2 - Write the augmented matrix of the system and use...Ch. 6.2 - Use the Gauss-Jordan method to solve each of the...Ch. 6.2 - Prob. 44ECh. 6.2 - Prob. 45ECh. 6.2 - Prob. 46ECh. 6.2 - Prob. 47ECh. 6.2 - Prob. 48ECh. 6.2 - Prob. 49ECh. 6.2 - Prob. 55ECh. 6.2 - Prob. 50ECh. 6.2 - Prob. 51ECh. 6.2 - Prob. 52ECh. 6.2 - Prob. 53ECh. 6.2 - Prob. 54ECh. 6.2 - Prob. 56ECh. 6.2 - Prob. 57ECh. 6.2 - Prob. 58ECh. 6.2 - Prob. 59ECh. 6.2 - Prob. 60ECh. 6.2 - Prob. 61ECh. 6.2 - Prob. 62ECh. 6.2 - Solve the system by any method.
62.
Ch. 6.2 - Prob. 63ECh. 6.2 - Prob. 65ECh. 6.2 - Prob. 66ECh. 6.2 - Prob. 67ECh. 6.2 - Prob. 68ECh. 6.2 - Prob. 69ECh. 6.2 - Prob. 70ECh. 6.2 - Prob. 71ECh. 6.2 - 72. Explain why a system with more variables than...Ch. 6.3 - Checkpoint 1 In Example 1, suppose that the...Ch. 6.3 - Checkpoint 2 Write the augmented matrix of the...Ch. 6.3 - Prob. 3CPCh. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Prob. 3ECh. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Prob. 7ECh. 6.3 - Prob. 8ECh. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Prob. 10ECh. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Prob. 12ECh. 6.3 - Prob. 13ECh. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Prob. 16ECh. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - Use systems of equations to work these applied...Ch. 6.3 - A graphing calculator or other technology is...Ch. 6.3 - A graphing calculator or other technology is...Ch. 6.3 - 25. Social Science The table shows Census Bureau...Ch. 6.3 - 26. Social Science The table shows Census Bureau...Ch. 6.3 - 27. Business At a pottery factory, fuel...Ch. 6.3 - Prob. 28ECh. 6.4 - Checkpoint 1
Rewrite matrix M in Example 1 in a...Ch. 6.4 - Prob. 2CPCh. 6.4 - Prob. 3CPCh. 6.4 - Prob. 4CPCh. 6.4 - Prob. 5CPCh. 6.4 - Prob. 6CPCh. 6.4 - Prob. 7CPCh. 6.4 - Prob. 8CPCh. 6.4 - Prob. 9CPCh. 6.4 - Prob. 1ECh. 6.4 - Prob. 2ECh. 6.4 - Prob. 3ECh. 6.4 - Prob. 4ECh. 6.4 - Prob. 5ECh. 6.4 - Prob. 6ECh. 6.4 - Prob. 7ECh. 6.4 - Find the size of each of the given matrices....Ch. 6.4 - Prob. 9ECh. 6.4 - Prob. 10ECh. 6.4 - Prob. 11ECh. 6.4 - Perform the indicated operations where possible....Ch. 6.4 - Prob. 14ECh. 6.4 - Perform the indicated operations where possible....Ch. 6.4 - Prob. 15ECh. 6.4 - Prob. 16ECh. 6.4 - Prob. 17ECh. 6.4 - Let and . Find each of the following. (See...Ch. 6.4 - Prob. 19ECh. 6.4 - Let and . Find each of the following. (See...Ch. 6.4 - Prob. 21ECh. 6.4 - Let and . Find each of the following. (See...Ch. 6.4 - Prob. 23ECh. 6.4 - Prob. 24ECh. 6.4 - Prob. 25ECh. 6.4 - Prob. 26ECh. 6.4 - Prob. 27ECh. 6.4 - Using matrices
verify that the statements in...Ch. 6.4 - Prob. 29ECh. 6.4 - Prob. 30ECh. 6.4 - Work the following exercises. (See Example...Ch. 6.4 - Prob. 32ECh. 6.4 - Prob. 33ECh. 6.4 - Prob. 34ECh. 6.4 - Prob. 35ECh. 6.4 - Prob. 36ECh. 6.5 - Prob. 1CPCh. 6.5 - Prob. 2CPCh. 6.5 - Prob. 3CPCh. 6.5 - Prob. 4CPCh. 6.5 - Prob. 5CPCh. 6.5 - Prob. 6CPCh. 6.5 - Prob. 7CPCh. 6.5 - Prob. 8CPCh. 6.5 - Prob. 9CPCh. 6.5 - Prob. 1ECh. 6.5 - Prob. 2ECh. 6.5 - In Exercises 1-6, the sizes of two matrices A and...Ch. 6.5 - In Exercises 1-6, the sizes of two matrices A and...Ch. 6.5 - Prob. 5ECh. 6.5 - Prob. 6ECh. 6.5 - Prob. 7ECh. 6.5 - Prob. 8ECh. 6.5 - Prob. 9ECh. 6.5 - Prob. 10ECh. 6.5 - Find each of the following matrix products, if...Ch. 6.5 - Prob. 12ECh. 6.5 - Prob. 13ECh. 6.5 - Find each of the following matrix products, if...Ch. 6.5 - Prob. 15ECh. 6.5 - Prob. 16ECh. 6.5 - Prob. 17ECh. 6.5 - Find each of the following matrix products, if...Ch. 6.5 - Prob. 19ECh. 6.5 - Prob. 20ECh. 6.5 - Prob. 21ECh. 6.5 - Prob. 22ECh. 6.5 - Prob. 23ECh. 6.5 - Given matrices
verify that the statements in...Ch. 6.5 - Prob. 25ECh. 6.5 - Prob. 26ECh. 6.5 - Prob. 27ECh. 6.5 - Prob. 28ECh. 6.5 - Prob. 29ECh. 6.5 - Prob. 30ECh. 6.5 - Prob. 31ECh. 6.5 - Determine whether the given matrices are inverses...Ch. 6.5 - Prob. 37ECh. 6.5 - Prob. 34ECh. 6.5 - Prob. 35ECh. 6.5 - Find the inverse, if it exists, for each of the...Ch. 6.5 - Prob. 33ECh. 6.5 - Find the inverse, if it exists, for each of the...Ch. 6.5 - Prob. 39ECh. 6.5 - Prob. 40ECh. 6.5 - Find the inverse, if it exists, for each of the...Ch. 6.5 - Find the inverse, if it exists, for each of the...Ch. 6.5 - Prob. 43ECh. 6.5 - Prob. 44ECh. 6.5 - Prob. 45ECh. 6.5 - Prob. 46ECh. 6.5 - Prob. 47ECh. 6.5 - Prob. 48ECh. 6.5 - Prob. 49ECh. 6.5 - Work these exercises. (See Example 4.)
50. Bulk...Ch. 6.5 - Prob. 56ECh. 6.5 - A graphing calculator or other technology is...Ch. 6.5 - Prob. 55ECh. 6.5 - Prob. 52ECh. 6.5 - Prob. 53ECh. 6.5 - Prob. 54ECh. 6.6 - Prob. 1CPCh. 6.6 - Prob. 2CPCh. 6.6 - Prob. 3CPCh. 6.6 - Prob. 4CPCh. 6.6 - Prob. 5CPCh. 6.6 - Prob. 6CPCh. 6.6 - Prob. 7CPCh. 6.6 - Checkpoint 8
Use the following matrix to find the ...Ch. 6.6 - Prob. 9CPCh. 6.6 - Prob. 1ECh. 6.6 - Prob. 2ECh. 6.6 - Prob. 3ECh. 6.6 - Prob. 4ECh. 6.6 - Prob. 5ECh. 6.6 - Prob. 6ECh. 6.6 - Prob. 7ECh. 6.6 - Use the inverse of the coefficient matrix to solve...Ch. 6.6 - Prob. 9ECh. 6.6 - Prob. 10ECh. 6.6 - Prob. 11ECh. 6.6 - Use the inverse of the coefficient matrix to solve...Ch. 6.6 - Prob. 13ECh. 6.6 - Prob. 14ECh. 6.6 - Prob. 15ECh. 6.6 - Prob. 16ECh. 6.6 - Write a system of equations, and use the inverse...Ch. 6.6 - Prob. 18ECh. 6.6 - Prob. 20ECh. 6.6 - Prob. 19ECh. 6.6 - Write a system of equations, and use the inverse...Ch. 6.6 - 22. Health A 100-bed nursing home provides two...Ch. 6.6 - Find the production matrix for the given...Ch. 6.6 - Prob. 24ECh. 6.6 - Prob. 25ECh. 6.6 - Exercises 25 and 26 refer to Example 6.
Example 6...Ch. 6.6 - Work these problems. (See Examples 3-6.)
28....Ch. 6.6 - Prob. 27ECh. 6.6 - Prob. 29ECh. 6.6 - Work these problems. (See Examples...Ch. 6.6 - Prob. 31ECh. 6.6 - Prob. 32ECh. 6.6 - Prob. 33ECh. 6.6 - Prob. 34ECh. 6.6 - Prob. 35ECh. 6.6 - Prob. 36ECh. 6.6 - Work these coding exercises. (See Example 7 and...Ch. 6.6 - Prob. 38ECh. 6.6 - Prob. 39ECh. 6.6 - Prob. 40ECh. 6.6 - Prob. 41ECh. 6.6 - Prob. 42ECh. 6.6 - Prob. 43ECh. 6.6 - 44. Business The figure shows four southern cities...Ch. 6 - Prob. 1RECh. 6 - Solve each of the following systems.
2.
Ch. 6 - Solve each of the following systems.
3.
Ch. 6 - Solve each of the following systems.
4.
Ch. 6 - 5. Business Abigail Henderson plans to buy shares...Ch. 6 - Prob. 6RECh. 6 - Prob. 7RECh. 6 - Prob. 8RECh. 6 - Prob. 9RECh. 6 - Prob. 10RECh. 6 - Prob. 11RECh. 6 - Prob. 12RECh. 6 - Prob. 13RECh. 6 - Prob. 14RECh. 6 - Prob. 15RECh. 6 - Prob. 16RECh. 6 - Prob. 17RECh. 6 - Prob. 18RECh. 6 - Prob. 19RECh. 6 - Prob. 20RECh. 6 - Prob. 21RECh. 6 - Prob. 22RECh. 6 - Prob. 23RECh. 6 - Prob. 24RECh. 6 - Prob. 25RECh. 6 - Prob. 26RECh. 6 - Prob. 27RECh. 6 - Prob. 28RECh. 6 - Prob. 29RECh. 6 - Prob. 30RECh. 6 - Prob. 31RECh. 6 - Prob. 32RECh. 6 - Prob. 33RECh. 6 - Prob. 34RECh. 6 - Prob. 35RECh. 6 - Prob. 36RECh. 6 - Prob. 37RECh. 6 - Prob. 38RECh. 6 - Prob. 39RECh. 6 - Prob. 40RECh. 6 - Prob. 41RECh. 6 - Prob. 42RECh. 6 - Prob. 43RECh. 6 - Prob. 44RECh. 6 - Prob. 45RECh. 6 - Prob. 46RECh. 6 - Prob. 47RECh. 6 - Prob. 48RECh. 6 - Prob. 49RECh. 6 - Prob. 50RECh. 6 - Prob. 51RECh. 6 - Prob. 52RECh. 6 - Prob. 53RECh. 6 - Prob. 54RECh. 6 - Prob. 55RECh. 6 - Prob. 56RECh. 6 - Prob. 57RECh. 6 - Prob. 58RECh. 6 - Prob. 59RECh. 6 - Prob. 60RECh. 6 - Prob. 61RECh. 6 - Prob. 62RECh. 6 - Prob. 63RECh. 6 - Prob. 64RECh. 6 - Prob. 65RECh. 6 - Prob. 66RECh. 6 - Prob. 67RECh. 6 - Prob. 68RECh. 6 - Prob. 69RECh. 6 - Prob. 70RECh. 6 - Prob. 71RECh. 6 - Prob. 72RECh. 6 - Prob. 73RECh. 6 - Prob. 74RECh. 6 - Prob. 75RECh. 6 - Prob. 76RECh. 6 - Prob. 77RECh. 6 - Prob. 78RECh. 6 - Prob. 79RECh. 6 - Prob. 80RECh. 6 - Prob. 81RECh. 6 - Prob. 82RECh. 6 - Prob. 83RECh. 6 - Prob. 84RECh. 6 - Prob. 85RECh. 6 - Solve each of the following problems by any...Ch. 6 - Prob. 87RECh. 6 - Prob. 88RECh. 6 - Prob. 89RECh. 6 - Use technology to do Exercises 89-91.
90. Business...Ch. 6 - Prob. 91RECh. 6 - Prob. 92RECh. 6 - Prob. 93RECh. 6 - Prob. 94RECh. 6 - Prob. 95RECh. 6 - Prob. 96RECh. 6 - Prob. 1CECh. 6 - 2. It was shown previously that there are four...Ch. 6 - 3. Which trips in the Stampede Air network take...Ch. 6 - Prob. 4CECh. 6 - Prob. 5CECh. 6 - Prob. 6CE
Additional Math Textbook Solutions
Find more solutions based on key concepts
Heights Refer to the dotplot in the previous question. a. What is the height of a woman with a z-score of -1? b...
Introductory Statistics
The discount on the baseball glove.
Pre-Algebra Student Edition
Basis for the Range Rule of Thumb and the Empirical Rule. In Exercises 45–48, find the indicated area under the...
Elementary Statistics (13th Edition)
In Exercises 5-36, express all probabilities as fractions.
23. Combination Lock The typical combination lock us...
Elementary Statistics
1. How many solutions are there to ax + b = 0 with ?
College Algebra with Modeling & Visualization (5th Edition)
Fill in each blank so that the resulting statement is true. The quadratic function f(x)=a(xh)2+k,a0, is in ____...
Algebra and Trigonometry (6th Edition)
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, subject and related others by exploring similar questions and additional content below.Similar questions
- Are the two statements A and B equivalent? (A) p~q (B) ~pq ☐ Statement A and B are equivalent. ☐ Statement A and B are not equivalent as their values in three rows are not identical. ☐ Statement A and B are not equivalent as their values in one row is not identical. ☐ Statement A and B are not equivalent as their values in two row are not identical.arrow_forwardLet p, q and r to be True, False and True statements, respectively. What are the values of the statements below. A: B: [(p→q)^~q]→r (pvq) → ~r O O A: False B: False A: True B: True A: False B: True A: True B: Falsearrow_forwardLet's assume p and q are true statements. What are the values of the statements below. A: (p→ q) →~p B: (p v~q) → ~(p^q) A: True B: False A: True B: True ☐ A: A: False B: False ☐ A: False B: Truearrow_forward
- Three statements A, B and C are given below. Which choice is correct? (A) ~(p^~q) (B) ~p^q (c) pv~q ☐ All statements are inequivalent. ☐ Only statements A and B are equivalent. ☐ Only statements C and B are equivalent. ☐ Only statements A and C are equivalent.arrow_forward6: 000 Which truth table is correct for the given compound statement? (pvq)^p]→q A: B: P P 9 [(pvq)^p]→ 9 T T F T T T T F T T F F F T T F T F F F T F F T C: P 9 [(pvq)^p]→9 D: P 9 [pvq)^p]→9 T T T T T T TF T T F F F T F F T T F F F F F T B A D Previous Page Next Page Page 3 of 11arrow_forwardst One Which truth table is correct for the given compound statement? (p→q)^~p A: P q (p→q)^~p B: P q (p→q)^~p T T F T T F T F F T F T F T T F T T F F F F F T C: D: P q (p→ q)^~p P 9 (p→q)^~p T T F T T T T F F T F F F T T F T T F F T F F T A U Oarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Algebra: Structure And Method, Book 1AlgebraISBN:9780395977224Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. ColePublisher:McDougal Littell
Glencoe Algebra 1, Student Edition, 9780079039897...AlgebraISBN:9780079039897Author:CarterPublisher:McGraw Hill
College Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning
Elementary AlgebraAlgebraISBN:9780998625713Author:Lynn Marecek, MaryAnne Anthony-SmithPublisher:OpenStax - Rice University
Big Ideas Math A Bridge To Success Algebra 1: Stu...AlgebraISBN:9781680331141Author:HOUGHTON MIFFLIN HARCOURTPublisher:Houghton Mifflin Harcourt
Algebra: Structure And Method, Book 1
Algebra
ISBN:9780395977224
Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. Cole
Publisher:McDougal Littell
Glencoe Algebra 1, Student Edition, 9780079039897...
Algebra
ISBN:9780079039897
Author:Carter
Publisher:McGraw Hill
College Algebra (MindTap Course List)
Algebra
ISBN:9781305652231
Author:R. David Gustafson, Jeff Hughes
Publisher:Cengage Learning
Elementary Algebra
Algebra
ISBN:9780998625713
Author:Lynn Marecek, MaryAnne Anthony-Smith
Publisher:OpenStax - Rice University
Big Ideas Math A Bridge To Success Algebra 1: Stu...
Algebra
ISBN:9781680331141
Author:HOUGHTON MIFFLIN HARCOURT
Publisher:Houghton Mifflin Harcourt
UG/ linear equation in linear algebra; Author: The Gate Academy;https://www.youtube.com/watch?v=aN5ezoOXX5A;License: Standard YouTube License, CC-BY
System of Linear Equations-I; Author: IIT Roorkee July 2018;https://www.youtube.com/watch?v=HOXWRNuH3BE;License: Standard YouTube License, CC-BY