Finite Mathematics (11th Edition)
11th Edition
ISBN: 9780321979438
Author: Margaret L. Lial, Raymond N. Greenwell, Nathan P. Ritchey
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Videos
Textbook Question
Chapter 2.2, Problem 1E
Write the augmented matrix fur each system. Do not solve.
3 x + y = 6
2x + 5y = 15
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
Determine whether the lines
L₁ (t) = (-2,3, −1)t + (0,2,-3) and
L2 p(s) = (2, −3, 1)s + (-10, 17, -8)
intersect. If they do, find the point of intersection.
Convert the line given by the parametric equations y(t)
Enter the symmetric equations in alphabetic order.
(x(t)
= -4+6t
= 3-t
(z(t)
=
5-7t
to symmetric equations.
Find the point at which the line (t) = (4, -5,-4)+t(-2, -1,5) intersects the xy plane.
Chapter 2 Solutions
Finite Mathematics (11th Edition)
Ch. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 -
Use the echelon method to solve each system of...Ch. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 - Prob. 5ECh. 2.1 - Prob. 6ECh. 2.1 - Prob. 7ECh. 2.1 -
Use the echelon method to solve each system of...Ch. 2.1 - Prob. 9ECh. 2.1 - Prob. 10E
Ch. 2.1 -
Use the echelon method to solve each system of...Ch. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 - Prob. 15ECh. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 - Prob. 17ECh. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 - Use the echelon method to solve each system of two...Ch. 2.1 - Prob. 20ECh. 2.1 - An inconsistent system...Ch. 2.1 - Prob. 22ECh. 2.1 - Describe what a parameter is arid why it is used...Ch. 2.1 - In your own words, describe the echelon method as...Ch. 2.1 - Prob. 25ECh. 2.1 - Solve each system of equations. Let z be the...Ch. 2.1 - Solve each system of equations. Let z be the...Ch. 2.1 - Prob. 28ECh. 2.1 - Prob. 29ECh. 2.1 - For each of the following systems of equations in...Ch. 2.1 -
For each of the following systems of equations in...Ch. 2.1 - Prob. 32ECh. 2.1 - Prob. 33ECh. 2.1 - Prob. 34ECh. 2.1 -
Groceries If 20 lb of rice and 10 lb of potatoes...Ch. 2.1 -
36. Downloads Blake Allvine spent $35.97...Ch. 2.1 - Prob. 37ECh. 2.1 -
38. Sales An apparel shop sells skirts for $45...Ch. 2.1 - Prob. 39ECh. 2.1 -
40. Stock Lorri Morgan has $16,000 invested in...Ch. 2.1 - Banking A bank teller has a total of 70 bills in...Ch. 2.1 - Rug Cleaning Machines Kelly Karpet Kleaners sells...Ch. 2.1 - Prob. 43ECh. 2.1 - Prob. 44ECh. 2.1 - Prob. 45ECh. 2.1 - Prob. 46ECh. 2.1 - Prob. 47ECh. 2.1 -
48. Flight Time A flight leaves New York at 8...Ch. 2.1 -
49. The 24® Game The object of the 24 Game,...Ch. 2.2 -
Write the augmented matrix fur each system. Do...Ch. 2.2 -
Write the augmented matrix for each system. Do...Ch. 2.2 - Prob. 3ECh. 2.2 - Prob. 4ECh. 2.2 - Prob. 5ECh. 2.2 - Prob. 6ECh. 2.2 -
Write the system of equations associated with...Ch. 2.2 - Prob. 8ECh. 2.2 - Prob. 9ECh. 2.2 - Prob. 10ECh. 2.2 - Prob. 11ECh. 2.2 - Use the indicated row operations to change each...Ch. 2.2 - Prob. 13ECh. 2.2 - Prob. 14ECh. 2.2 - Prob. 15ECh. 2.2 - Prob. 16ECh. 2.2 - Prob. 17ECh. 2.2 - Prob. 18ECh. 2.2 - Prob. 19ECh. 2.2 - Prob. 20ECh. 2.2 - Use the Gauss-Jordan method to solve each system...Ch. 2.2 - Use the Gauss-Jordan method to solve each system...Ch. 2.2 - Prob. 23ECh. 2.2 - Prob. 24ECh. 2.2 - Prob. 25ECh. 2.2 - Use the Gauss-Jordan method to solve each system...Ch. 2.2 - Prob. 27ECh. 2.2 -
Use the Gauss-Jordan method to solve each system...Ch. 2.2 - Prob. 29ECh. 2.2 - Prob. 30ECh. 2.2 - Prob. 31ECh. 2.2 - Prob. 32ECh. 2.2 - Prob. 33ECh. 2.2 - Prob. 34ECh. 2.2 - Prob. 35ECh. 2.2 - Prob. 36ECh. 2.2 - Prob. 37ECh. 2.2 - Prob. 38ECh. 2.2 - Prob. 39ECh. 2.2 - Prob. 40ECh. 2.2 - Prob. 41ECh. 2.2 - Prob. 42ECh. 2.2 -
43. On National Public Radio, the "Weekend...Ch. 2.2 - Prob. 44ECh. 2.2 - Investments Katherine Chong invests $10,000...Ch. 2.2 -
46. Office Technology Pyro-Tech, Inc. is...Ch. 2.2 - Prob. 47ECh. 2.2 - Prob. 48ECh. 2.2 - Loans To get the necessary funds for a planned...Ch. 2.2 - Manufacturing Nadir, Inc. produces three models of...Ch. 2.2 -
51. Deliveries An electronics company produces...Ch. 2.2 - Tents L.L. Bean makes three sizes of Ultra Dome...Ch. 2.2 - Transportation A manufacturer purchases a part for...Ch. 2.2 - APPLY IT Transportation An auto manufacturer sends...Ch. 2.2 - Prob. 55ECh. 2.2 -
56. Packaging A company produces four...Ch. 2.2 - Prob. 57ECh. 2.2 - Animal Breeding An animal breeder can buy four...Ch. 2.2 - Prob. 59ECh. 2.2 - Prob. 60ECh. 2.2 - Prob. 61ECh. 2.2 - Prob. 62ECh. 2.2 - Prob. 63ECh. 2.2 - Prob. 64ECh. 2.2 -
65. Modeling War One of the factors that...Ch. 2.2 - Prob. 66ECh. 2.2 -
67. Baseball Ichiro Suzuki holds the American...Ch. 2.2 - Prob. 68ECh. 2.2 -
69. Toys One hundred toys are to be given out to...Ch. 2.2 - Prob. 70ECh. 2.2 - Prob. 71ECh. 2.2 - Prob. 72ECh. 2.2 - Prob. 73ECh. 2.3 - Prob. 1ECh. 2.3 - Prob. 2ECh. 2.3 - Prob. 3ECh. 2.3 - Prob. 4ECh. 2.3 - Decide whether each statement is true or false. If...Ch. 2.3 - Prob. 6ECh. 2.3 - Prob. 7ECh. 2.3 - Prob. 8ECh. 2.3 - Prob. 9ECh. 2.3 - Prob. 10ECh. 2.3 - Prob. 11ECh. 2.3 - Prob. 12ECh. 2.3 - Prob. 13ECh. 2.3 - Prob. 14ECh. 2.3 - Prob. 15ECh. 2.3 - Prob. 16ECh. 2.3 - Prob. 17ECh. 2.3 - Prob. 18ECh. 2.3 - Prob. 19ECh. 2.3 - Prob. 20ECh. 2.3 - Prob. 21ECh. 2.3 - Prob. 22ECh. 2.3 - Prob. 23ECh. 2.3 - Prob. 24ECh. 2.3 - Prob. 25ECh. 2.3 - Prob. 26ECh. 2.3 - Prob. 27ECh. 2.3 - Prob. 28ECh. 2.3 - Prob. 29ECh. 2.3 - Prob. 30ECh. 2.3 - Prob. 31ECh. 2.3 - Prob. 32ECh. 2.3 - For matrices X=[ xyzw] and 0=[ 0000], find the...Ch. 2.3 - Prob. 34ECh. 2.3 - Prob. 35ECh. 2.3 - Prob. 36ECh. 2.3 - Prob. 37ECh. 2.3 - Prob. 38ECh. 2.3 - Prob. 39ECh. 2.3 - Prob. 40ECh. 2.3 - Prob. 41ECh. 2.3 -
42. Trading Partners The table below gives, the...Ch. 2.3 - Prob. 43ECh. 2.3 - Prob. 44ECh. 2.3 - Testing Medication A drug company is testing 200...Ch. 2.3 - Prob. 46ECh. 2.3 - Prob. 47ECh. 2.3 - Prob. 48ECh. 2.3 - Prob. 49ECh. 2.3 - Prob. 50ECh. 2.4 - Let A=[ -2-403] and B=[ -6240]. Find each value....Ch. 2.4 - Prob. 2ECh. 2.4 - Prob. 3ECh. 2.4 - Prob. 4ECh. 2.4 - Prob. 5ECh. 2.4 -
Let and Find each value.
6. 7B– 3A
Ch. 2.4 - Prob. 7ECh. 2.4 - Prob. 8ECh. 2.4 - Prob. 9ECh. 2.4 - Prob. 10ECh. 2.4 - Prob. 11ECh. 2.4 - Prob. 12ECh. 2.4 - To find the product matrix AB, the number of...Ch. 2.4 - Prob. 14ECh. 2.4 - Prob. 15ECh. 2.4 - Prob. 16ECh. 2.4 - Prob. 17ECh. 2.4 - Prob. 18ECh. 2.4 -
Find each matrix product, if possible.
19.
Ch. 2.4 - Find each matrix product, if possible. [...Ch. 2.4 - Prob. 21ECh. 2.4 - Prob. 22ECh. 2.4 - Prob. 23ECh. 2.4 - Prob. 24ECh. 2.4 - Prob. 25ECh. 2.4 - Prob. 26ECh. 2.4 - Prob. 27ECh. 2.4 - Prob. 28ECh. 2.4 - Prob. 29ECh. 2.4 - Prob. 30ECh. 2.4 - Prob. 31ECh. 2.4 - Prob. 32ECh. 2.4 - Prob. 33ECh. 2.4 - Prob. 34ECh. 2.4 - Prob. 35ECh. 2.4 - Prob. 36ECh. 2.4 -
Given matrices
verify that the statements in...Ch. 2.4 - Prob. 38ECh. 2.4 - Prob. 39ECh. 2.4 - Prob. 40ECh. 2.4 - Prob. 41ECh. 2.4 - Prob. 42ECh. 2.4 - Use a computer or graphing calculator arid the...Ch. 2.4 - Prob. 44ECh. 2.4 - Prob. 45ECh. 2.4 - Prob. 46ECh. 2.4 - Prob. 47ECh. 2.4 - Prob. 48ECh. 2.4 - Prob. 49ECh. 2.4 - Prob. 50ECh. 2.4 - Prob. 51ECh. 2.4 - Prob. 52ECh. 2.4 - Prob. 53ECh. 2.4 - Prob. 54ECh. 2.4 - Prob. 55ECh. 2.4 - 56. Northern Spotted Owl Population In an attempt...Ch. 2.4 -
57. World Population The 2010 birth and death...Ch. 2.5 - Prob. 1ECh. 2.5 -
Decide whether the given matrices are inverses...Ch. 2.5 - Prob. 3ECh. 2.5 - Decide whether the given matrices are inverses of...Ch. 2.5 - Decide whether the given matrices are inverses of...Ch. 2.5 - Prob. 6ECh. 2.5 - Prob. 7ECh. 2.5 - Prob. 8ECh. 2.5 - Prob. 9ECh. 2.5 - Prob. 10ECh. 2.5 - Prob. 11ECh. 2.5 - Prob. 12ECh. 2.5 - Prob. 13ECh. 2.5 - Prob. 14ECh. 2.5 - Prob. 15ECh. 2.5 - Prob. 16ECh. 2.5 - Prob. 17ECh. 2.5 - Prob. 18ECh. 2.5 - Prob. 19ECh. 2.5 - Prob. 20ECh. 2.5 - Prob. 21ECh. 2.5 - Prob. 22ECh. 2.5 - Find the inverse, if it exists, for each matrix. [...Ch. 2.5 - Prob. 24ECh. 2.5 - Prob. 25ECh. 2.5 - Prob. 26ECh. 2.5 - Prob. 27ECh. 2.5 -
Solve each system of equations by using the...Ch. 2.5 -
Solve each system of equations by using the...Ch. 2.5 - Prob. 30ECh. 2.5 - Prob. 31ECh. 2.5 - Prob. 32ECh. 2.5 - Prob. 33ECh. 2.5 -
Solve each system of equations by using the...Ch. 2.5 -
Solve each system of equations by using the...Ch. 2.5 - Prob. 36ECh. 2.5 - Prob. 37ECh. 2.5 - Prob. 38ECh. 2.5 - Prob. 39ECh. 2.5 - Prob. 40ECh. 2.5 - Prob. 41ECh. 2.5 - Prob. 42ECh. 2.5 - Prob. 43ECh. 2.5 - Prob. 44ECh. 2.5 - Prob. 45ECh. 2.5 - Prob. 46ECh. 2.5 - Prob. 47ECh. 2.5 - Prob. 48ECh. 2.5 - Prob. 49ECh. 2.5 - Prob. 50ECh. 2.5 - Prob. 51ECh. 2.5 - Prob. 52ECh. 2.5 - Prob. 53ECh. 2.5 - Prob. 54ECh. 2.5 - Prob. 55ECh. 2.5 - Prob. 56ECh. 2.5 - Prob. 57ECh. 2.5 - Prob. 58ECh. 2.5 - Prob. 59ECh. 2.5 - Prob. 60ECh. 2.5 - Prob. 61ECh. 2.5 - Solve each exercise by using the inverse of the...Ch. 2.5 - Prob. 63ECh. 2.5 -
Solve each exercise by using the inverse of the...Ch. 2.5 - Prob. 65ECh. 2.5 -
Solve each exercise by using the inverse of the...Ch. 2.6 -
Find the production matrix for the following...Ch. 2.6 - Prob. 2ECh. 2.6 - Prob. 3ECh. 2.6 - Prob. 4ECh. 2.6 - Prob. 5ECh. 2.6 - Prob. 6ECh. 2.6 - Prob. 7ECh. 2.6 - Find the ratios of products A, B, and C using a...Ch. 2.6 - Prob. 9ECh. 2.6 - Use a graphing calculator or computer to find the...Ch. 2.6 - Prob. 11ECh. 2.6 -
Input-Output Open Model In Exercises 11 and 12,...Ch. 2.6 - Prob. 13ECh. 2.6 - Prob. 14ECh. 2.6 - Input-Output Open Model In Exercises 13-16, refer...Ch. 2.6 - Input-Output Open Model In Exercises 13- refer to...Ch. 2.6 - Input-Output Open Model A primitive economy...Ch. 2.6 - Prob. 18ECh. 2.6 - Prob. 19ECh. 2.6 - Prob. 20ECh. 2.6 -
21. Israeli Economy An analysis of the 1958...Ch. 2.6 -
22. Chinese Economy The 1981 Chinese economy can...Ch. 2.6 - Prob. 23ECh. 2.6 - Prob. 24ECh. 2.6 - Prob. 25ECh. 2.6 - Prob. 26ECh. 2.6 -
27. Input-Output Closed Model Use the...Ch. 2.6 - Input-Output Closed Model Suppose that production...Ch. 2.6 - Prob. 29ECh. 2 - Find the second-order contact matrix PQ mentioned...Ch. 2 - Prob. 2EACh. 2 - Prob. 3EACh. 2 - Prob. 4EACh. 2 - Prob. 5EACh. 2 - Prob. 1RECh. 2 - Determine whether each of the following statements...Ch. 2 - Prob. 3RECh. 2 - Prob. 4RECh. 2 - Prob. 5RECh. 2 - Prob. 6RECh. 2 - Prob. 7RECh. 2 - Prob. 8RECh. 2 - Prob. 9RECh. 2 - Prob. 10RECh. 2 - Prob. 11RECh. 2 - Prob. 12RECh. 2 - Prob. 13RECh. 2 - Prob. 14RECh. 2 - Prob. 15RECh. 2 - Prob. 16RECh. 2 - Prob. 17RECh. 2 - Prob. 18RECh. 2 -
Solve each system by the echelon method.
19. 2x -...Ch. 2 - Prob. 20RECh. 2 - Solve each system by the echelon method. 2x - 3y +...Ch. 2 - Prob. 22RECh. 2 - Prob. 23RECh. 2 - Prob. 24RECh. 2 - Prob. 25RECh. 2 - Prob. 26RECh. 2 - Prob. 27RECh. 2 - Prob. 28RECh. 2 - Prob. 29RECh. 2 - Prob. 30RECh. 2 - Prob. 31RECh. 2 - Prob. 32RECh. 2 - Prob. 33RECh. 2 - Prob. 34RECh. 2 - Prob. 35RECh. 2 - Prob. 36RECh. 2 - Prob. 37RECh. 2 - Prob. 38RECh. 2 - Prob. 39RECh. 2 - Given the matrices A=[ 4102369],B=[ 232240012],C=[...Ch. 2 - Prob. 41RECh. 2 - Prob. 42RECh. 2 - Prob. 43RECh. 2 - Prob. 44RECh. 2 - Prob. 45RECh. 2 - Prob. 46RECh. 2 - Prob. 47RECh. 2 - Prob. 48RECh. 2 - Prob. 49RECh. 2 - Prob. 50RECh. 2 - Prob. 51RECh. 2 - Find the inverse of each matrix that has an...Ch. 2 - Prob. 53RECh. 2 - Prob. 54RECh. 2 - Prob. 55RECh. 2 - Prob. 56RECh. 2 - Prob. 57RECh. 2 - Prob. 58RECh. 2 - Prob. 59RECh. 2 - Prob. 60RECh. 2 - Prob. 61RECh. 2 - Prob. 62RECh. 2 - Prob. 63RECh. 2 - Prob. 64RECh. 2 - Prob. 65RECh. 2 - Prob. 66RECh. 2 - Prob. 67RECh. 2 - Prob. 68RECh. 2 - Prob. 69RECh. 2 - Prob. 70RECh. 2 - Prob. 71RECh. 2 - Filling Orders A printer has three orders for...Ch. 2 -
73. Input-Output An economy depends on two...Ch. 2 -
74. Nebraska The 1970 economy of the state of...Ch. 2 - Prob. 75RECh. 2 - Prob. 76RECh. 2 - Prob. 77RECh. 2 - Prob. 78RECh. 2 - Prob. 79RECh. 2 - Prob. 80RECh. 2 - Prob. 81RECh. 2 - Prob. 82RECh. 2 - Prob. 83RECh. 2 -
84. Baseball In the 2009 Major League Baseball...Ch. 2 - Prob. 85RE
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
- Find the distance from the point (-9, -3, 0) to the line ä(t) = (−4, 1, −1)t + (0, 1, −3) .arrow_forward1 Find a vector parallel to the line defined by the parametric equations (x(t) = -2t y(t) == 1- 9t z(t) = -1-t Additionally, find a point on the line.arrow_forwardFind the (perpendicular) distance from the line given by the parametric equations (x(t) = 5+9t y(t) = 7t = 2-9t z(t) to the point (-1, 1, −3).arrow_forward
- Let ä(t) = (3,-2,-5)t + (7,−1, 2) and (u) = (5,0, 3)u + (−3,−9,3). Find the acute angle (in degrees) between the lines:arrow_forwardNo chatgpt pls will upvotearrow_forwardA tank initially contains 50 gal of pure water. Brine containing 3 lb of salt per gallon enters the tank at 2 gal/min, and the (perfectly mixed) solution leaves the tank at 3 gal/min. Thus, the tank is empty after exactly 50 min. (a) Find the amount of salt in the tank after t minutes. (b) What is the maximum amount of salt ever in the tank?arrow_forward
- Draw a picture of a normal distribution with mean 70 and standard deviation 5.arrow_forwardWhat do you guess are the standard deviations of the two distributions in the previous example problem?arrow_forward1 What is the area of triangle ABC? 12 60° 60° A D B A 6√√3 square units B 18√3 square units 36√3 square units D 72√3 square unitsarrow_forward
- Each answer must be justified and all your work should appear. You will be marked on the quality of your explanations. You can discuss the problems with classmates, but you should write your solutions sepa- rately (meaning that you cannot copy the same solution from a joint blackboard, for exam- ple). Your work should be submitted on Moodle, before February 7 at 5 pm. 1. True or false: (a) if E is a subspace of V, then dim(E) + dim(E) = dim(V) (b) Let {i, n} be a basis of the vector space V, where v₁,..., Un are all eigen- vectors for both the matrix A and the matrix B. Then, any eigenvector of A is an eigenvector of B. Justify. 2. Apply Gram-Schmidt orthogonalization to the system of vectors {(1,2,-2), (1, −1, 4), (2, 1, 1)}. 3. Suppose P is the orthogonal projection onto a subspace E, and Q is the orthogonal projection onto the orthogonal complement E. (a) The combinations of projections P+Q and PQ correspond to well-known oper- ators. What are they? Justify your answer. (b) Show…arrow_forwardpleasd dont use chat gptarrow_forward1. True or false: (a) if E is a subspace of V, then dim(E) + dim(E+) = dim(V) (b) Let {i, n} be a basis of the vector space V, where vi,..., are all eigen- vectors for both the matrix A and the matrix B. Then, any eigenvector of A is an eigenvector of B. Justify. 2. Apply Gram-Schmidt orthogonalization to the system of vectors {(1, 2, -2), (1, −1, 4), (2, 1, 1)}. 3. Suppose P is the orthogonal projection onto a subspace E, and Q is the orthogonal projection onto the orthogonal complement E. (a) The combinations of projections P+Q and PQ correspond to well-known oper- ators. What are they? Justify your answer. (b) Show that P - Q is its own inverse. 4. Show that the Frobenius product on n x n-matrices, (A, B) = = Tr(B*A), is an inner product, where B* denotes the Hermitian adjoint of B. 5. Show that if A and B are two n x n-matrices for which {1,..., n} is a basis of eigen- vectors (for both A and B), then AB = BA. Remark: It is also true that if AB = BA, then there exists a common…arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
College Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning
Elementary Linear Algebra (MindTap Course List)AlgebraISBN:9781305658004Author:Ron LarsonPublisher:Cengage Learning
Algebra for College StudentsAlgebraISBN:9781285195780Author:Jerome E. Kaufmann, Karen L. SchwittersPublisher:Cengage Learning
Algebra: Structure And Method, Book 1AlgebraISBN:9780395977224Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. ColePublisher:McDougal Littell
Elementary AlgebraAlgebraISBN:9780998625713Author:Lynn Marecek, MaryAnne Anthony-SmithPublisher:OpenStax - Rice University
College Algebra (MindTap Course List)
Algebra
ISBN:9781305652231
Author:R. David Gustafson, Jeff Hughes
Publisher:Cengage Learning
Elementary Linear Algebra (MindTap Course List)
Algebra
ISBN:9781305658004
Author:Ron Larson
Publisher:Cengage Learning
Algebra for College Students
Algebra
ISBN:9781285195780
Author:Jerome E. Kaufmann, Karen L. Schwitters
Publisher:Cengage Learning
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
Elementary Algebra
Algebra
ISBN:9780998625713
Author:Lynn Marecek, MaryAnne Anthony-Smith
Publisher:OpenStax - Rice University
Matrix Factorization - Numberphile; Author: Numberphile;https://www.youtube.com/watch?v=wTUSz-HSaBg;License: Standard YouTube License, CC-BY