Student Solutions Manual For Zill's A First Course In Differential Equations With Modeling Applications, 11th
11th Edition
ISBN: 9781305965737
Author: Dennis G. Zill
Publisher: Brooks Cole
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
thumb_up100%
Chapter 2.2, Problem 4E
In Problems 1–22 solve the given differential equation by separation of variables.
4.
Expert Solution & Answer
Trending nowThis is a popular solution!
Students have asked these similar questions
t
56
65
33
Solution:
Solution:
7.2
2x²+5x-3.
Diagram:
till
sh
one
The Steps
the same technique as in 4 and 5) above to factor the following
Show all the Steps.
"Diagram,
(2)
03)
But
(be
Wha
x+2
3
Q/ solving Laplace equation on Rectangular Rejon
a xx+uyy = o
u (x, 0) = u(x,2) = 0
u
(o,y) = y
(1,y) = 27
Chapter 2 Solutions
Student Solutions Manual For Zill's A First Course In Differential Equations With Modeling Applications, 11th
Ch. 2.1 - In Problems 14 reproduce the given...Ch. 2.1 - In Problems 14 reproduce the given...Ch. 2.1 - dydx=1xy (a) y(0) = 0 (b) y(1) = 0 (c) y(2) = 2...Ch. 2.1 - In Problems 14 reproduce the given...Ch. 2.1 - In Problems 512 use computer software to obtain a...Ch. 2.1 - In Problems 512 use computer software to obtain a...Ch. 2.1 - In Problems 512 use computer software to obtain a...Ch. 2.1 - In Problems 512 use computer software to obtain a...Ch. 2.1 - In Problems 512 use computer software to obtain a...Ch. 2.1 - In Problems 512 use computer software to obtain a...
Ch. 2.1 - In Problems 512 use computer software to obtain a...Ch. 2.1 - In Problems 512 use computer software to obtain a...Ch. 2.1 - In Problems 13 and 14 the given figure represents...Ch. 2.1 - In Problems 13 and 14 the given figure represents...Ch. 2.1 - In parts (a) and (b) sketch isoclines f(x, y) = c...Ch. 2.1 - (a) Consider the direction field of the...Ch. 2.1 - Consider the autonomous first-order differential...Ch. 2.1 - Consider the autonomous first-order differential...Ch. 2.1 - In Problems 21-28 find the critical points and...Ch. 2.1 - In Problems 21-28 find the critical points and...Ch. 2.1 - In Problems 21-28 find the critical points and...Ch. 2.1 - In Problems 21-28 find the critical points and...Ch. 2.1 - In Problems 21-28 find the critical points and...Ch. 2.1 - In Problems 21-28 find the critical points and...Ch. 2.1 - In Problems 21-28 find the critical points and...Ch. 2.1 - Prob. 28ECh. 2.1 - In Problems 29 and 30 consider the autonomous...Ch. 2.1 - In Problems 29 and 30 consider the autonomous...Ch. 2.1 - Consider the autonomous DE dy/dx = (2/)y sin y...Ch. 2.1 - A critical point c of an autonomous first-order DE...Ch. 2.1 - Suppose that y(x) is a nonconstant solution of the...Ch. 2.1 - Prob. 34ECh. 2.1 - Using the autonomous equation (2), discuss how it...Ch. 2.1 - Prob. 36ECh. 2.1 - Suppose the autonomous DE in (2) has no critical...Ch. 2.1 - Population Model The differential equation in...Ch. 2.1 - Population Model Another population model is given...Ch. 2.1 - Terminal Velocity In Section 1.3 we saw that the...Ch. 2.1 - Suppose the model in Problem 40 is modified so...Ch. 2.1 - Chemical reactions When certain kinds of chemicals...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 122 solve the given differential...Ch. 2.2 - In Problems 2328 find an explicit solution of the...Ch. 2.2 - In Problems 2328 find an explicit solution of the...Ch. 2.2 - In Problems 2328 find an explicit solution of the...Ch. 2.2 - In Problems 2328 find an explicit solution of the...Ch. 2.2 - In Problems 2328 find an explicit solution of the...Ch. 2.2 - In Problems 2328 find an explicit solution of the...Ch. 2.2 - In Problems 29 and 30 proceed as in Example 5 and...Ch. 2.2 - In Problems 29 and 30 proceed as in Example 5 and...Ch. 2.2 - In Problems 3134 find an explicit solution of the...Ch. 2.2 - In Problems 3134 find an explicit solution of the...Ch. 2.2 - In Problems 3134 find an explicit solution of the...Ch. 2.2 - In Problems 3134 find an explicit solution of the...Ch. 2.2 - (a) Find a solution of the initial-value problem...Ch. 2.2 - Find a solution of xdydx=y2y that passes through...Ch. 2.2 - Find a singular solution of Problem 21. Of Problem...Ch. 2.2 - Show that an implicit solution of...Ch. 2.2 - Often a radical change in the form of the solution...Ch. 2.2 - Often a radical change in the form of the solution...Ch. 2.2 - Often a radical change in the form of the solution...Ch. 2.2 - Often a radical change in the form of the solution...Ch. 2.2 - Every autonomous first-order equation dy/dx = f(y)...Ch. 2.2 - (a) The autonomous first-order differential...Ch. 2.2 - In Problems 4550 use a technique of integration or...Ch. 2.2 - In Problems 4550 use a technique of integration or...Ch. 2.2 - In Problems 4550 use a technique of integration or...Ch. 2.2 - In Problems 4550 use a technique of integration or...Ch. 2.2 - In Problems 4550 use a technique of integration or...Ch. 2.2 - In Problems 4550 use a technique of integration or...Ch. 2.2 - Prob. 51ECh. 2.2 - Prob. 52ECh. 2.2 - In Problems 43 and 44 we saw that every autonomous...Ch. 2.2 - Prob. 54ECh. 2.2 - Find a function whose square plus the square of...Ch. 2.2 - Prob. 56ECh. 2.2 - Prob. 57ECh. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 1-24 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - Prob. 22ECh. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 124 find the general solution of the...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 2536 solve the given initial-value...Ch. 2.3 - In Problems 3740 proceed as in Example 6 to solve...Ch. 2.3 - In Problems 3740 proceed as in Example 6 to solve...Ch. 2.3 - In Problems 3740 proceed as in Example 6 to solve...Ch. 2.3 - In Problems 3740 proceed as in Example 6 to solve...Ch. 2.3 - In Problems 41 and 42 proceed as in Example 6 to...Ch. 2.3 - In Problems 41 and 42 proceed as in Example 6 to...Ch. 2.3 - In Problems 43 and 44 proceed as in Example 7 and...Ch. 2.3 - Prob. 44ECh. 2.3 - In Problems 45 and 46 proceed as in Example 7 and...Ch. 2.3 - Prob. 46ECh. 2.3 - Prob. 47ECh. 2.3 - Prob. 48ECh. 2.3 - Prob. 49ECh. 2.3 - Prob. 50ECh. 2.3 - Reread Example 4 and then find the general...Ch. 2.3 - Reread the discussion following Example 5....Ch. 2.3 - Prob. 53ECh. 2.3 - Prob. 54ECh. 2.3 - In determining the integrating factor (3), we did...Ch. 2.3 - Prob. 56ECh. 2.3 - Radioactive Decay Series The following system of...Ch. 2.3 - Heart Pacemaker A heart pacemaker consists of a...Ch. 2.3 - Prob. 61ECh. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In Problems 120 determine whether the given...Ch. 2.4 - In problems 2126 slove the given initial-value...Ch. 2.4 - In Problem 2126 solve the given initial-value...Ch. 2.4 - In problems 2126 solve the given intial-value...Ch. 2.4 - In Problems 2126 solve the given initial-value...Ch. 2.4 - In Problems 2126 solve the given initial-value...Ch. 2.4 - In Problems 2126 solve the given initial-value...Ch. 2.4 - In Problems 27 and 28 find the value of k so that...Ch. 2.4 - In Problems 27 and 28 find the value of k so that...Ch. 2.4 - In Problems 29 and 30 verify that the given...Ch. 2.4 - In Problems 29 and 30 verify that the given...Ch. 2.4 - In Problems 3136 solve the given differential...Ch. 2.4 - In Problems 3136 solve the given differential...Ch. 2.4 - In Problems 3136 solve the given differential...Ch. 2.4 - In Problems 3136 solve the given differential...Ch. 2.4 - In Problems 3136 solve the given differential...Ch. 2.4 - In Problems 3136 solve the given differential...Ch. 2.4 - In Problems 37 and 38 solve the given...Ch. 2.4 - In Problems 37 and 38 solve the given...Ch. 2.4 - (a) Show that a one-parameter family of solutions...Ch. 2.4 - Prob. 40ECh. 2.4 - Prob. 41ECh. 2.4 - Discuss how the functions M(x, y) and N(x, y) can...Ch. 2.4 - Differential equations are sometimes solved by...Ch. 2.4 - True or False: Every separable first-order...Ch. 2.4 - Falling Chain A portion of a uniform chain of...Ch. 2.5 - Each DE in Problems 114 is homogeneous. In...Ch. 2.5 - In Problems 110 solve the given differential...Ch. 2.5 - In Problems 110 solve the given differential...Ch. 2.5 - In Problems 1-10 solve the given differential...Ch. 2.5 - In Problems 110 solve the given differential...Ch. 2.5 - In Problems 1-10 solve the given differential...Ch. 2.5 - In Problems 110 solve the given differential...Ch. 2.5 - In Problems 110 solve the given differential...Ch. 2.5 - In Problems 110 solve the given differential...Ch. 2.5 - In Problems 110 solve the given differential...Ch. 2.5 - In Problems 1114 solve the given initial-value...Ch. 2.5 - In Problems 1114 solve the given initial-value...Ch. 2.5 - In Problems 1114 solve the given initial-value...Ch. 2.5 - In Problems 1114 solve the given initial-value...Ch. 2.5 - In Problems 1520 solve the given differential...Ch. 2.5 - In Problems 1520 solve the given differential...Ch. 2.5 - In Problems 1520 solve the given differential...Ch. 2.5 - In Problems 1520 solve the given differential...Ch. 2.5 - In Problems 1520 solve the given differential...Ch. 2.5 - In Problems 1520 solve the given differential...Ch. 2.5 - In Problems 21 and 22 solve the given...Ch. 2.5 - In Problems 21 and 22 solve the given...Ch. 2.5 - In Problems 2328 solve the given differential...Ch. 2.5 - In Problems 2328 solve the given differential...Ch. 2.5 - In Problems 2328 solve the given differential...Ch. 2.5 - In Problems 2328 solve the given differential...Ch. 2.5 - In Problems 2328 solve the given differential...Ch. 2.5 - In Problems 2328 solve the given differential...Ch. 2.5 - dydx=cos(x+y), y(0) = /4Ch. 2.5 - In Problems 29 and 30 solve the given...Ch. 2.5 - Explain why it is always possible to express any...Ch. 2.5 - Put the homogeneous differential equation...Ch. 2.5 - Prob. 33ECh. 2.5 - Prob. 34ECh. 2.5 - The differential equation dy/dx = P(x) + Q(x)y +...Ch. 2.5 - Determine an appropriate substitution to solve...Ch. 2.5 - Falling Chain In Problem 45 in Exercises 2.4 we...Ch. 2.5 - Population Growth In the study of population...Ch. 2.6 - In Problems 1 and 2 use Eulers method to obtain a...Ch. 2.6 - In Problems 1 and 2 use Eulers method to obtain a...Ch. 2.6 - In Problems 3 and 4 use Eulers method to obtain a...Ch. 2.6 - In Problems 3 and 4 use Eulers method to obtain a...Ch. 2.6 - In Problems 510 use a numerical solver and Eulers...Ch. 2.6 - In Problems 510 use a numerical solver and Eulers...Ch. 2.6 - In Problems 510 use a numerical solver and Eulers...Ch. 2.6 - In Problems 510 use a numerical solver and Eulers...Ch. 2.6 - In Problems 510 use a numerical solver and Eulers...Ch. 2.6 - In Problems 510 use a numerical solver and Eulers...Ch. 2 - Answer Problems 112 without referring back to the...Ch. 2 - Prob. 2RECh. 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 - In Problems 13 and 14 construct an autonomous...Ch. 2 - The number 0 is a critical point of the autonomous...Ch. 2 - Prob. 16RECh. 2 - Prob. 17RECh. 2 - Classify each differential equation as separable,...Ch. 2 - In Problems 1926 solve the given differential...Ch. 2 - In Problems 1926 solve the given differential...Ch. 2 - Prob. 21RECh. 2 - In Problems 1926 solve the given differential...Ch. 2 - In Problems 1926 solve the given differential...Ch. 2 - In Problems 1926 solve the given differential...Ch. 2 - In Problems 1926 solve the given differential...Ch. 2 - In Problems 1926 solve the given differential...Ch. 2 - In Problems 2730 express the solution of the given...Ch. 2 - In Problems 2730 express the solution of the given...Ch. 2 - Prob. 29RECh. 2 - Prob. 30RECh. 2 - Prob. 31RECh. 2 - In Problems 31 and 32 solve the given...Ch. 2 - Prob. 33RECh. 2 - Prob. 34RECh. 2 - (a) Without solving, explain why the initial-value...Ch. 2 - (a) Find an implicit solution of the initial-value...Ch. 2 - Prob. 37RECh. 2 - Use Eulers method with step size h = 0.1 to...
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
- Solve the following equation forx. leave answer in Simplified radical form. 5x²-4x-3=6arrow_forwardMATCHING LIST Question 6 Listen Use the given equations and their discriminants to match them to the type and number of solutions. 00 ed two irrational solutions a. x²+10x-2=-24 two rational solutions b. 8x²+11x-3=7 one rational solution c. 3x²+2x+7=2 two non-real solutions d. x²+12x+45 = 9 DELL FLOWER CHILD 10/20 All Changes S $681 22991arrow_forward88 MULTIPLE CHOICE Question 7 Listen The following irrational expression is given in unsimplified form with four op- tions in simplified form. Select the correct simplified form. Select only one option. A 2±3√√2 B 4±√3 2±√ √3 D 1±√√3 DELL FLOWER CHILD 11/200 4 ± √48 4 ✓ All Changes Saved 165arrow_forward
- Q / solving ha place equation a x x + u y y = 0 u (x, 0)=0 u ( x, 2) = 10 u (o,y) = 4 (119)=0 и on Rectangular Rejonarrow_forward(a) Test the hypothesis. Consider the hypothesis test Ho = : against H₁o < 02. Suppose that the sample sizes aren₁ = 7 and n₂ = 13 and that $² = 22.4 and $22 = 28.2. Use α = 0.05. Ho is not ✓ rejected. 9-9 IV (b) Find a 95% confidence interval on of 102. Round your answer to two decimal places (e.g. 98.76).arrow_forwardLet us suppose we have some article reported on a study of potential sources of injury to equine veterinarians conducted at a university veterinary hospital. Forces on the hand were measured for several common activities that veterinarians engage in when examining or treating horses. We will consider the forces on the hands for two tasks, lifting and using ultrasound. Assume that both sample sizes are 6, the sample mean force for lifting was 6.2 pounds with standard deviation 1.5 pounds, and the sample mean force for using ultrasound was 6.4 pounds with standard deviation 0.3 pounds. Assume that the standard deviations are known. Suppose that you wanted to detect a true difference in mean force of 0.25 pounds on the hands for these two activities. Under the null hypothesis, 40 = 0. What level of type II error would you recommend here? Round your answer to four decimal places (e.g. 98.7654). Use a = 0.05. β = i What sample size would be required? Assume the sample sizes are to be equal.…arrow_forward
- = Consider the hypothesis test Ho: μ₁ = μ₂ against H₁ μ₁ μ2. Suppose that sample sizes are n₁ = 15 and n₂ = 15, that x1 = 4.7 and X2 = 7.8 and that s² = 4 and s² = 6.26. Assume that o and that the data are drawn from normal distributions. Use απ 0.05. (a) Test the hypothesis and find the P-value. (b) What is the power of the test in part (a) for a true difference in means of 3? (c) Assuming equal sample sizes, what sample size should be used to obtain ẞ = 0.05 if the true difference in means is - 2? Assume that α = 0.05. (a) The null hypothesis is 98.7654). rejected. The P-value is 0.0008 (b) The power is 0.94 . Round your answer to four decimal places (e.g. Round your answer to two decimal places (e.g. 98.76). (c) n₁ = n2 = 1 . Round your answer to the nearest integer.arrow_forwardConsider the hypothesis test Ho: = 622 against H₁: 6 > 62. Suppose that the sample sizes are n₁ = 20 and n₂ = 8, and that = 4.5; s=2.3. Use a = 0.01. (a) Test the hypothesis. Round your answers to two decimal places (e.g. 98.76). The test statistic is fo = i The critical value is f = Conclusion: i the null hypothesis at a = 0.01. (b) Construct the confidence interval on 02/022 which can be used to test the hypothesis: (Round your answer to two decimal places (e.g. 98.76).) iarrow_forwardConjecture Let x and y be integers. If x is even and y is odd, then xy is even. Try some examples. Does the conjecture seem to be true or false?arrow_forward
- Find the general solution to the differential equationarrow_forward3. A room has a large circular table with ten seats, numbered 1 to 10, such that to the right of seat number i is seat number i + 1 for all i ∈ {1, . . . , 9} and to the right of seat 10 is seat 1. We want to assign seats to 10 people, 6 of them only speak Slovene, 1 of them only speaks English, and the remaining 3 speak both Slovene and English, by giving out numbered place cards. In how many ways can we do that so that everyone sits next to at least one person who speaks a common language?arrow_forwardcharity savings Budget for May travel food Peter earned $700 during May. The graph shows how the money was used. What fraction was clothes? O Search Submit clothes leisurearrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Discrete Mathematics and Its Applications ( 8th I...MathISBN:9781259676512Author:Kenneth H RosenPublisher:McGraw-Hill Education
Mathematics for Elementary Teachers with Activiti...MathISBN:9780134392790Author:Beckmann, SybillaPublisher:PEARSON
Thinking Mathematically (7th Edition)MathISBN:9780134683713Author:Robert F. BlitzerPublisher:PEARSON
Discrete Mathematics With ApplicationsMathISBN:9781337694193Author:EPP, Susanna S.Publisher:Cengage Learning,
Pathways To Math Literacy (looseleaf)MathISBN:9781259985607Author:David Sobecki Professor, Brian A. MercerPublisher:McGraw-Hill Education
Discrete Mathematics and Its Applications ( 8th I...
Math
ISBN:9781259676512
Author:Kenneth H Rosen
Publisher:McGraw-Hill Education
Mathematics for Elementary Teachers with Activiti...
Math
ISBN:9780134392790
Author:Beckmann, Sybilla
Publisher:PEARSON
Thinking Mathematically (7th Edition)
Math
ISBN:9780134683713
Author:Robert F. Blitzer
Publisher:PEARSON
Discrete Mathematics With Applications
Math
ISBN:9781337694193
Author:EPP, Susanna S.
Publisher:Cengage Learning,
Pathways To Math Literacy (looseleaf)
Math
ISBN:9781259985607
Author:David Sobecki Professor, Brian A. Mercer
Publisher:McGraw-Hill Education
01 - What Is A Differential Equation in Calculus? Learn to Solve Ordinary Differential Equations.; Author: Math and Science;https://www.youtube.com/watch?v=K80YEHQpx9g;License: Standard YouTube License, CC-BY
Higher Order Differential Equation with constant coefficient (GATE) (Part 1) l GATE 2018; Author: GATE Lectures by Dishank;https://www.youtube.com/watch?v=ODxP7BbqAjA;License: Standard YouTube License, CC-BY
Solution of Differential Equations and Initial Value Problems; Author: Jefril Amboy;https://www.youtube.com/watch?v=Q68sk7XS-dc;License: Standard YouTube License, CC-BY