
Linear Algebra and Its Applications, Books a la Carte Edition Plus MyLab Math with Pearson eText -- Access Code Card (5th Edition)
5th Edition
ISBN: 9780321989925
Author: David C. Lay, Steven R. Lay, Judi J. McDonald
Publisher: PEARSON
expand_more
expand_more
format_list_bulleted
Textbook Question
Chapter 6.2, Problem 4PP
Let U be an n × n matrix with orthonormal columns. Show that det U = ±1.
Expert Solution & Answer

Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
ma Classes
Term. Spring 2025
Title
Details
Credit Hours
CRN
Schedule Type
Grade Mode
Level
Date
Status
Message
*MATHEMATICS FOR MANAGEME...
MTH 245, 400
4
54835
Online
Normal Grading Mode
Ecampus Undergradu... 03/21/2025
Registered
**Web Registered...
*SOIL SCIENCE
CSS 205, 400
0
52298
Online
Normal Grading Mode
Undergraduate
03/21/2025
Waitlisted
Waitlist03/21/2025
PLANT PATHOLOGY
BOT 451, 400
4
56960
Online
Normal Grading Mode
Undergraduate
03/21/2025
Registered
**Web Registered...
Records: 3
Schedule
Schedule Details
Here is an augmented matrix for a system of equations (three equations and three variables). Let the
variables used be x, y, and z:
1 2 4 6
0 1
-1
3
0
0
1
4
Note: that this matrix is already in row echelon form.
Your goal is to use this row echelon form to revert back to the equations that this represents, and then to
ultimately solve the system of equations by finding x, y and z.
Input your answer as a coordinate point: (x,y,z) with no spaces.
1
3 -4
In the following matrix
perform the operation 2R1 + R2 → R2.
-2 -1
6
After you have completed this, what numeric value is in the a22 position?
Chapter 6 Solutions
Linear Algebra and Its Applications, Books a la Carte Edition Plus MyLab Math with Pearson eText -- Access Code Card (5th Edition)
Ch. 6.1 - Let a = [21] and b = [31]. Compute abaa and...Ch. 6.1 - Let c = [4/312/3] and d = [561]. a. Find a unit...Ch. 6.1 - Let W be a subspace of Rn. Exercise 30 establishes...Ch. 6.1 - Compute the quantities in Exercises 18 using the...Ch. 6.1 - Compute the quantities in Exercises 18 using the...Ch. 6.1 - Compute the quantities in Exercises 18 using the...Ch. 6.1 - Compute the quantities in Exercises 18 using the...Ch. 6.1 - Compute the quantities in Exercises 18 using the...Ch. 6.1 - Compute the quantities in Exercises 18 using the...Ch. 6.1 - Compute the quantities in Exercises 18 using the...
Ch. 6.1 - Compute the quantities in Exercises 18 using the...Ch. 6.1 - In Exercises 912, find a unit vector in the...Ch. 6.1 - In Exercises 912, find a unit vector in the...Ch. 6.1 - In Exercises 912, find a unit vector in the...Ch. 6.1 - Prob. 12ECh. 6.1 - Find the distance between x = [103] and y = [15].Ch. 6.1 - Find the distance between u = [052] and z = [418].Ch. 6.1 - Determine which pairs of vectors in Exercises 1518...Ch. 6.1 - Determine which pairs of vectors in Exercises 1518...Ch. 6.1 - Determine which pairs of vectors in Exercises 1518...Ch. 6.1 - Determine which pairs of vectors in Exercises 1518...Ch. 6.1 - In Exercises 19 and 20, all vectors are in n. Mark...Ch. 6.1 - In Exercises 19 and 20, all vectors are in n. Mark...Ch. 6.1 - Use the transpose definition of the inner product...Ch. 6.1 - Prob. 22ECh. 6.1 - Let u = [251] and v = [746]. Compute and compare...Ch. 6.1 - Verify the parallelogram law for vectors u and v...Ch. 6.1 - Let v = [ab] Describe the set H of vectors [xy]...Ch. 6.1 - Let u = [567], and let W be the set of all x in 3...Ch. 6.1 - Suppose a vector y is orthogonal to vectors u and...Ch. 6.1 - Suppose y is orthogonal to u and v. Show that y is...Ch. 6.1 - Let W = Span {v1,,vp}. Show that if x is...Ch. 6.1 - Let W be a subspace of n, and let W be the set of...Ch. 6.1 - Show that if x is in both W and W, then x = 0.Ch. 6.2 - Let u1= [1/52/5] and u2= [2/51/5]. Show that {u1....Ch. 6.2 - Let y and L be as in Example 3 and Figure 3....Ch. 6.2 - Let U and x be as in Example 6. and let y = [326]....Ch. 6.2 - Let U be an n n matrix with orthonormal columns....Ch. 6.2 - In Exercises 16, determine which sets of vectors...Ch. 6.2 - In Exercises 16, determine which sets of vectors...Ch. 6.2 - In Exercises 16, determine which sets of vectors...Ch. 6.2 - In Exercises 16, determine which sets of vectors...Ch. 6.2 - In Exercises 16, determine which sets of vectors...Ch. 6.2 - In Exercises 16, determine which sets of vectors...Ch. 6.2 - In Exercises 710, show that {u1, u2} or {u1, u2,...Ch. 6.2 - In Exercises 710, show that {u1, u2} or {u1, u2,...Ch. 6.2 - In Exercises 710, show that {u1, u2} or {u1, u2,...Ch. 6.2 - In Exercises 710, show that {u1, u2} or {u1, u2,...Ch. 6.2 - Compute the orthogonal projection of [17] onto the...Ch. 6.2 - Compute the orthogonal projection of [11] onto the...Ch. 6.2 - Let y = [23] and u = [47] Write y as the sum of...Ch. 6.2 - Let y = [26] and u = [71] Write y as the sum of a...Ch. 6.2 - Let y = [31] and u = [86] Compute the distance...Ch. 6.2 - Let y = [39] and u = [12] Compute the distance...Ch. 6.2 - In Exercises 1722, determine which sets of vectors...Ch. 6.2 - In Exercises 1722, determine which sets of vectors...Ch. 6.2 - In Exercises 1722, determine which sets of vectors...Ch. 6.2 - In Exercises 1722, determine which sets of vectors...Ch. 6.2 - In Exercises 1722, determine which sets of vectors...Ch. 6.2 - In Exercises 1722, determine which sets of vectors...Ch. 6.2 - In Exercises 23 and 24, all vectors are in n. Mark...Ch. 6.2 - In Exercises 23 and 24, all vectors are in n. Mark...Ch. 6.2 - Prove Theorem 7. [Hint: For (a), compute |Ux||2,...Ch. 6.2 - Suppose W is a sub space of n spanned by n nonzero...Ch. 6.2 - Let U be a square matrix with orthonormal columns....Ch. 6.2 - Let U be an n n orthogonal matrix. Show that the...Ch. 6.2 - Let U and V be n n orthogonal matrices. Explain...Ch. 6.2 - Let U be an orthogonal matrix, and construct V by...Ch. 6.2 - Show that the orthogonal projection of a vector y...Ch. 6.2 - Let {v1, v2} be an orthogonal set of nonzero...Ch. 6.2 - Prob. 33ECh. 6.2 - Given u 0 in n, let L = Span{u}. For y in n, the...Ch. 6.3 - Let u1 = [714], u2 = [112], x = [916], and W =...Ch. 6.3 - Let W be a subspace of n. Let x and y be vectors...Ch. 6.3 - In Exercises 1 and 2, you may assume that {u1,,...Ch. 6.3 - u1 = [1211], u2 = [2111], u3 = [1121], u4 =...Ch. 6.3 - In Exercises 36, verify that {u1, u2} is an...Ch. 6.3 - In Exercises 36, verify that {u1, u2} is an...Ch. 6.3 - In Exercises 36, verify that {u1, u2} is an...Ch. 6.3 - In Exercises 36, verify that {u1, u2} is an...Ch. 6.3 - In Exercises 710, let W be the subspace spanned by...Ch. 6.3 - In Exercises 710, let W be the subspace spanned by...Ch. 6.3 - In Exercises 710, let W be the subspace spanned by...Ch. 6.3 - In Exercises 710, let W be the subspace spanned by...Ch. 6.3 - In Exercises 11 and 12, find the closest point to...Ch. 6.3 - In Exercises 11 and 12, find the closest point to...Ch. 6.3 - In Exercises 13 and 14, find the best...Ch. 6.3 - In Exercises 13 and 14, find the best...Ch. 6.3 - Let y = [595], u1 = [351], u2 = [321]. Find die...Ch. 6.3 - Let y, v1, and v2 be as in Exercise 12. Find the...Ch. 6.3 - Let y = [481], u1 = [2/31/32/3], u2 = [2/32/31/3],...Ch. 6.3 - Let y = [79], u1 = [1/103/10], and W = Span {u1}....Ch. 6.3 - Let u1 = [112], u2 = [512], and u3 = [001].Note...Ch. 6.3 - Let u1 and u2 be as in Exercise 19, and let u4 =...Ch. 6.3 - In Exercises 21 and 22, all vectors and subspaces...Ch. 6.3 - In Exercises 21 and 22, all vectors and subspaces...Ch. 6.3 - Let A be an m m matrix. Prove that every vector x...Ch. 6.3 - Let W be a subspace of n with an orthogonal basis...Ch. 6.4 - Let W = Span {x1, x2}, where x1 = [111] and x2 =...Ch. 6.4 - Suppose A = QR, where Q is an m n matrix with...Ch. 6.4 - In Exercises 1-6, the given set is a basis for a...Ch. 6.4 - In Exercises 1-6, the given set is a basis for a...Ch. 6.4 - In Exercises 1-6, the given set is a basis for a...Ch. 6.4 - In Exercises 1-6, the given set is a basis for a...Ch. 6.4 - In Exercises 1-6, the given set is a basis for a...Ch. 6.4 - In Exercises 1-6, the given set is a basis for a...Ch. 6.4 - Find an orthonormal basis of the subspace spanned...Ch. 6.4 - Find an orthonormal basis of the subspace spanned...Ch. 6.4 - Find an orthogonal basis for the column space of...Ch. 6.4 - Find an orthogonal basis for the column space of...Ch. 6.4 - Find an orthogonal basis for the column space of...Ch. 6.4 - Find an orthogonal basis for the column space of...Ch. 6.4 - In Exercises 13 and 14, the columns of Q were...Ch. 6.4 - In Exercises 13 and 14, the columns of Q were...Ch. 6.4 - Find a QR factorization of the matrix in Exercise...Ch. 6.4 - Find a QR factorization of the matrix in Exercise...Ch. 6.4 - In Exercises 17 and 18, all vectors and subspaces...Ch. 6.4 - In Exercises 17 and 18, all vectors and subspaces...Ch. 6.4 - Suppose A = QR, where Q is m n and R is n n....Ch. 6.4 - Suppose A = QR, where R is an invertible matrix....Ch. 6.4 - Given A = QR as in Theorem 12, describe how to...Ch. 6.4 - Let u1, , up be an orthogonal basis for a subspace...Ch. 6.4 - Suppose A = QR is a QR factorization of an m n...Ch. 6.4 - [M] Use the Gram-Schmidt process as in Example 2...Ch. 6.4 - [M] Use the method in this section to produce a QR...Ch. 6.5 - Let A = [133151172] and b = [535]. Find a...Ch. 6.5 - What can you say about the least-squares solution...Ch. 6.5 - In Exercises 1-4, find a least-squares solution of...Ch. 6.5 - In Exercises 1-4, find a least-squares solution of...Ch. 6.5 - In Exercises 1-4, find a least-squares solution of...Ch. 6.5 - In Exercises 1-4, find a least-squares solution of...Ch. 6.5 - In Exercises 5 and 6, describe all least-squares...Ch. 6.5 - In Exercises 5 and 6, describe all least-squares...Ch. 6.5 - Compute the least-squares error associated with...Ch. 6.5 - Compute the least-squares error associated with...Ch. 6.5 - In Exercises 9-12, find (a) the orthogonal...Ch. 6.5 - In Exercises 9-12, find (a) the orthogonal...Ch. 6.5 - In Exercises 9-12, find (a) the orthogonal...Ch. 6.5 - In Exercises 9-12, find (a) the orthogonal...Ch. 6.5 - Let A = [342134], b = [1195], u = [51], and v =...Ch. 6.5 - Let A = [213432], b = [544], u = [45], and v =...Ch. 6.5 - In Exercises 15 and 16, use the factorization A =...Ch. 6.5 - In Exercises 15 and 16, use the factorization A =...Ch. 6.5 - In Exercises 17 and 18, A is an m n matrix and b...Ch. 6.5 - a. If b is in the column space of A, then every...Ch. 6.5 - Let A be an m n matrix. Use the steps below to...Ch. 6.5 - Let A be an m n matrix such that ATA is...Ch. 6.5 - Let A be an m n matrix whose columns are linearly...Ch. 6.5 - Use Exercise 19 to show that rank ATA = rank A....Ch. 6.5 - Suppose A is m n with linearly independent...Ch. 6.5 - Find a formula for the least-squares solution of...Ch. 6.5 - Describe all least-squares solutions of the system...Ch. 6.6 - When the monthly sales of a product are subject to...Ch. 6.6 - In Exercises 1-4, find the equation y = 0 + 1x of...Ch. 6.6 - In Exercises 1-4, find the equation y = 0 + 1x of...Ch. 6.6 - In Exercises 1-4, find the equation y = 0 + 1x of...Ch. 6.6 - In Exercises 1-4, find the equation y = 0 + 1x of...Ch. 6.6 - Let X be the design matrix used to find the...Ch. 6.6 - Let X be the design matrix in Example 2...Ch. 6.6 - A certain experiment produces the data (1, 7.9),...Ch. 6.6 - Let x=1n(x1++xn) and y=1n(y1++yn). Show that the...Ch. 6.6 - Derive the normal equations (7) from the matrix...Ch. 6.6 - Use a matrix inverse to solve the system of...Ch. 6.6 - a. Rewrite the data in Example 1 with new...Ch. 6.6 - Suppose the x-coordinates of the data (x1, y1), ,...Ch. 6.6 - Exercises 19 and 20 involve a design matrix X with...Ch. 6.6 - Show that X2=TXTy. [Hint: Rewrite the left side...Ch. 6.7 - Use the inner product axioms to verify the...Ch. 6.7 - Use the inner product axioms to verify the...Ch. 6.7 - Let 2 have the inner product of Example 1, and let...Ch. 6.7 - Let 2 have the inner product of Example 1. Show...Ch. 6.7 - Exercises 3-8 refer to 2 with the inner product...Ch. 6.7 - Exercises 3-8 refer to 2 with the inner product...Ch. 6.7 - Exercises 3-8 refer to 2 with the inner product...Ch. 6.7 - Exercises 3-8 refer to 2 with the inner product...Ch. 6.7 - Exercises 3-8 refer to 2 with the inner product...Ch. 6.7 - Exercises 3-8 refer to 2 with the inner product...Ch. 6.7 - Let 3 have the inner product given by evaluation...Ch. 6.7 - Let 3 have the inner product as in Exercise 9,...Ch. 6.7 - Let p0, p1, and p2 be the orthogonal polynomials...Ch. 6.7 - Find a polynomial p3 such that {p0, p1, p2, p3}...Ch. 6.7 - Let A be any invertible n n matrix. Show that for...Ch. 6.7 - Let T be a one-to-one linear transformation from a...Ch. 6.7 - Use the inner product axioms and other results of...Ch. 6.7 - Use the inner product axioms and other results of...Ch. 6.7 - Use the inner product axioms and other results of...Ch. 6.7 - Use the inner product axioms and other results of...Ch. 6.7 - Given a 0 and b 0, let u=[ab] and v=[ba]. Use...Ch. 6.7 - Let u=[ab] and v=[11]. Use the Cauchy-Schwarz...Ch. 6.7 - Exercises 21-24 refer to V = C[0, 1], with the...Ch. 6.7 - Exercises 21-24 refer to V = C[0, 1], with the...Ch. 6.7 - Compute f for f in Exercise 21. Exercises 21-24...Ch. 6.7 - Compute g for g in Exercise 22. Exercises 21-24...Ch. 6.7 - Let V be the space C[1, 1] with the inner product...Ch. 6.7 - Let V be the space C[2, 2] with the inner product...Ch. 6.8 - Let q1(t) = 1, q2(t) = t, and q3(t) = 3t2 4....Ch. 6.8 - Find the first-order and third-order Fourier...Ch. 6.8 - Find the least-squares line y = 0 + 1x that best...Ch. 6.8 - Suppose 5 out of 25 data points in a weighted...Ch. 6.8 - Fit a cubic trend function to the data in Example...Ch. 6.8 - To make a trend analysis of six evenly spaced data...Ch. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - Prob. 7ECh. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - In Exercises 5-14, the space is C[0, 2] with the...Ch. 6.8 - [M] Refer to the data in Exercise 13 in Section...Ch. 6.8 - [M] Let f4 and f5 be the fourth-order and...Ch. 6 - Prob. 1SECh. 6 - Prob. 2SECh. 6 - Let {v1, , vp} be an orthonormal set in n. Verify...Ch. 6 - Let U be an n n orthogonal matrix. Show that if...Ch. 6 - Show that if an n n matrix U satisfies (Ux) (Uy)...Ch. 6 - Show that if U is an orthogonal matrix, then any...Ch. 6 - A Householder matrix, or an elementary reflector,...Ch. 6 - Let T: n n be a linear transformation that...Ch. 6 - Let u and v be linearly independent vectors in n...Ch. 6 - Suppose the columns of A are linearly independent....Ch. 6 - If a, b, and c are distinct numbers, then the...Ch. 6 - Consider the problem of finding an eigenvalue of...Ch. 6 - Use the steps below to prove the following...Ch. 6 - Explain why an equation Ax = b has a solution if...Ch. 6 - Exercises 15 and 16 concern the (real) Schur...Ch. 6 - Let A be an n n matrix with n real eigenvalues,...
Additional Math Textbook Solutions
Find more solutions based on key concepts
23. A plant nursery sells two sizes of oak trees to landscapers. Large trees cost the nursery $120 from the gro...
College Algebra (Collegiate Math)
CHECK POINT I Consider the six jokes about books by Groucho Marx. Bob Blitzer. Steven Wright, HennyYoungman. Je...
Thinking Mathematically (6th Edition)
Evaluate the integrals in Exercises 1–46.
1.
University Calculus: Early Transcendentals (4th Edition)
Check Your Understanding
Reading Check Complete each sentence using > or < for □.
RC1. 3 dm □ 3 dam
Basic College Mathematics
1. How is a sample related to a population?
Elementary Statistics: Picturing the World (7th Edition)
Let F be a continuous distribution function. If U is uniformly distributed on (0,1), find the distribution func...
A First Course in Probability (10th Edition)
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, algebra and related others by exploring similar questions and additional content below.Similar questions
- 5 -2 0 1 6 12 Let A = 6 7 -1 and B = 1/2 3 -14 -2 0 4 4 4 0 Compute -3A+2B and call the resulting matrix R. If rij represent the individual entries in the matrix R, what numeric value is in 131? Input your answer as a numeric value only.arrow_forward1 -2 4 10 My goal is to put the matrix 5 -1 1 0 into row echelon form using Gaussian elimination. 3 -2 6 9 My next step is to manipulate this matrix using elementary row operations to get a 0 in the a21 position. Which of the following operations would be the appropriate elementary row operation to use to get a 0 in the a21 position? O (1/5)*R2 --> R2 ○ 2R1 + R2 --> R2 ○ 5R1+ R2 --> R2 O-5R1 + R2 --> R2arrow_forwardThe 2x2 linear system of equations -2x+4y = 8 and 4x-3y = 9 was put into the following -2 4 8 augmented matrix: 4 -3 9 This augmented matrix is then converted to row echelon form. Which of the following matrices is the appropriate row echelon form for the given augmented matrix? 0 Option 1: 1 11 -2 Option 2: 4 -3 9 Option 3: 10 ܂ -2 -4 5 25 1 -2 -4 Option 4: 0 1 5 1 -2 Option 5: 0 0 20 -4 5 ○ Option 1 is the appropriate row echelon form. ○ Option 2 is the appropriate row echelon form. ○ Option 3 is the appropriate row echelon form. ○ Option 4 is the appropriate row echelon form. ○ Option 5 is the appropriate row echelon form.arrow_forward
- Let matrix A have order (dimension) 2x4 and let matrix B have order (dimension) 4x4. What results when you compute A+B? The resulting matrix will have dimensions of 2x4. ○ The resulting matrix will be a single number (scalar). The resulting matrix will have dimensions of 4x4. A+B is undefined since matrix A and B do not have the same dimensions.arrow_forwardIf -1 "[a446]-[254] 4b = -1 , find the values of a and b. ○ There is no solution for a and b. ○ There are infinite solutions for a and b. O a=3, b=3 O a=1, b=2 O a=2, b=1 O a=2, b=2arrow_forwardA student puts a 3x3 system of linear equations is into an augmented matrix. The student then correctly puts the augmented matrix into row echelon form (REF), which yields the following resultant matrix: -2 3 -0.5 10 0 0 0 -2 0 1 -4 Which of the following conclusions is mathematically supported by the work shown about system of linear equations? The 3x3 system of linear equations has no solution. ○ The 3x3 system of linear equations has infinite solutions. The 3x3 system of linear equations has one unique solution.arrow_forward
- Solve the following system of equations using matrices: -2x + 4y = 8 and 4x - 3y = 9 Note: This is the same system of equations referenced in Question 14. If a single solution exists, express your solution as an (x,y) coordinate point with no spaces. If there are infinite solutions write inf and if there are no solutions write ns in the box.arrow_forwardI need help explaining on this examplearrow_forwardConsider the table of values below. x y 2 64 3 48 4 36 5 27 Fill in the right side of the equation y= with an expression that makes each ordered pari (x,y) in the table a solution to the equation.arrow_forward
- solving for xarrow_forwardConsider the table of values below. x y 2 63 3 70 4 77 5 84 Fill in the right side of the equation y= with an expression that makes each ordered pari (x,y) in the table a solution to the equation.arrow_forwardThere were 426 books sold in one week. The number of biology books sold was 5 times that of the number of psychology books. How many books each were sold?arrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Algebra & Trigonometry with Analytic GeometryAlgebraISBN:9781133382119Author:SwokowskiPublisher:CengageElementary Linear Algebra (MindTap Course List)AlgebraISBN:9781305658004Author:Ron LarsonPublisher:Cengage LearningElements Of Modern AlgebraAlgebraISBN:9781285463230Author:Gilbert, Linda, JimmiePublisher:Cengage Learning,
- Linear Algebra: A Modern IntroductionAlgebraISBN:9781285463247Author:David PoolePublisher:Cengage LearningCollege Algebra (MindTap Course List)AlgebraISBN:9781305652231Author:R. David Gustafson, Jeff HughesPublisher:Cengage Learning
Algebra & Trigonometry with Analytic Geometry
Algebra
ISBN:9781133382119
Author:Swokowski
Publisher:Cengage

Elementary Linear Algebra (MindTap Course List)
Algebra
ISBN:9781305658004
Author:Ron Larson
Publisher:Cengage Learning

Elements Of Modern Algebra
Algebra
ISBN:9781285463230
Author:Gilbert, Linda, Jimmie
Publisher:Cengage Learning,

Linear Algebra: A Modern Introduction
Algebra
ISBN:9781285463247
Author:David Poole
Publisher:Cengage Learning


College Algebra (MindTap Course List)
Algebra
ISBN:9781305652231
Author:R. David Gustafson, Jeff Hughes
Publisher:Cengage Learning
HOW TO FIND DETERMINANT OF 2X2 & 3X3 MATRICES?/MATRICES AND DETERMINANTS CLASS XII 12 CBSE; Author: Neha Agrawal Mathematically Inclined;https://www.youtube.com/watch?v=bnaKGsLYJvQ;License: Standard YouTube License, CC-BY
What are Determinants? Mathematics; Author: Edmerls;https://www.youtube.com/watch?v=v4_dxD4jpgM;License: Standard YouTube License, CC-BY