Mathematical Methods in the Physical Sciences
Mathematical Methods in the Physical Sciences
3rd Edition
ISBN: 9780471198260
Author: Mary L. Boas
Publisher: Wiley, John & Sons, Incorporated
bartleby

Concept explainers

Differential Equations
Have you ever observed the movement of the satellites and rockets or how the planets go around the sun in their orbits? How will you determine their motion? Definitely they follow some scientific laws and these kinds of problems are framed as differentia…
bartleby

Videos

Textbook Question
Book Icon
Chapter 2.5, Problem 24P

Find each of the following in rectangular ( a + b i ) form if z = 2 − 3 i ;   i f   z = x + i y .

z / z ¯

Expert Solution & Answer
Check Mark

Want to see the full answer?

Check out a sample textbook solution
Blurred answer
Previous
Chapter 2.5, Problem 23P
Next
Chapter 2.5, Problem 25P
Students have asked these similar questions
A. Solve the following equations: Dand V 6. y" - 3y' + 2y = 2x2 + ex + 2xe* + 4e
Verify that              a.(b x c) = b.(c x a) = c. (a x b) if               a =4i – 3j +6k ,  b= 5i +4j – 3k ,  c = 4i + 6j +3 k
Find the paler form of Z= 1 +4i

Chapter 2 Solutions

Mathematical Methods in the Physical Sciences

Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...
Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.4 - For each of the following numbers, first visualize...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - First simplify each of the following numbers to...Ch. 2.5 - Find each of the following in rectangular (a+bi)...Ch. 2.5 - Find each of the following in rectangular (a+bi)...Ch. 2.5 - Find each of the following in rectangular (a+bi)...Ch. 2.5 - Find each of the following in rectangular (a+bi)...Ch. 2.5 - Find each of the following in rectangular (a+bi)...Ch. 2.5 - Find each of the following in rectangular (a+bi)...Ch. 2.5 - Prove that the conjugate of the quotient of two...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Find the absolute value of each of the following...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Solve for all possible values of the real numbers...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Describe geometrically the set of points in the...Ch. 2.5 - Show that z1z2 is the distance between the points...Ch. 2.5 - Find x and y as functions of t for the example...Ch. 2.5 - Find and a if z=(1it)/(2t+i).Ch. 2.5 - Find and a if z=cos2t+isin2t. Can you describe...Ch. 2.6 - Prove that an absolutely convergent series of...Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Test each of the following series for convergence....Ch. 2.6 - Prove that a series of complex terms diverges if...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Find the disk on convergence for each of the...Ch. 2.7 - Verify the series in (7.3) by computer. Also show...Ch. 2.8 - Show from the power series (8.1) that...Ch. 2.8 - Show from the power series (8.1) that ddzez=ezCh. 2.8 - Find the power series for excosx and for exsinx...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Express the following complex numbers in the x+iy...Ch. 2.9 - Show that for any real y,eiy=1. Hence show that...Ch. 2.9 - Show that the absolute value of a product of two...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Use Problems 27 and 28 to find the following...Ch. 2.9 - Prob. 38PCh. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Follow steps (a), (b), (c) above to find all the...Ch. 2.10 - Using the fact that a complex equation is really...Ch. 2.10 - As in Problem 27, find the formulas for sin3 and...Ch. 2.10 - Show that the center of mass of three identical...Ch. 2.10 - Show that the sum of the three cube roots of 8 is...Ch. 2.10 - Show that the sum of the n nth roots of any...Ch. 2.10 - The three cube roots of +1 are often called...Ch. 2.10 - Verify the results given for the roots in Example...Ch. 2.11 - Define sin z and Cos z by their power series....Ch. 2.11 - Solve the equations ei=cosisin,forcosandsin and so...Ch. 2.11 - Find each of the following in rectangular form...Ch. 2.11 - Find each of the following in rectangular form...Ch. 2.11 - Find each of the following in rectangular form...Ch. 2.11 - Find each of the following in rectangular form...Ch. 2.11 - Find each of the following in rectangular form...Ch. 2.11 - Find each of the following in rectangular form...Ch. 2.11 - Find each of the following in rectangular form...Ch. 2.11 - Find each of the following in rectangular form...Ch. 2.11 - In the following integrals express the sines and...Ch. 2.11 - In the following integrals express the sines and...Ch. 2.11 - In the following integrals express the sines and...Ch. 2.11 - In the following integrals express the sines and...Ch. 2.11 - In the following integrals express the sines and...Ch. 2.11 - In the following integrals express the sines and...Ch. 2.11 - Evaluate eax(acosbx+bsinbx)a2+b2 and take real...Ch. 2.11 - Evaluate e(a+ib)xdx and take real and imaginary...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Verify each of the following by using equations...Ch. 2.12 - Show that enz=(coshz+sinhz)n=coshnz+sinhnz. Use...Ch. 2.12 - Use a computer to plot graphs of sinh x, cosh x,...Ch. 2.12 - Using (12.2) and (8. l), find, in summation form,...Ch. 2.12 - Find the real part, the imaginary part and the...Ch. 2.12 - Find the real part, the imaginary part and the...Ch. 2.12 - Find the real part, the imaginary part and the...Ch. 2.12 - Find the real part, the imaginary part and the...Ch. 2.12 - Find the real part, the imaginary part and the...Ch. 2.12 - Find the real part, the imaginary part and the...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - Find each of the following in the x+iy form and...Ch. 2.12 - The functions sin t, cos t, …, are called...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Prob. 12PCh. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Evaluate each if the following in x+iy, and...Ch. 2.14 - Show that (ab)c can have more values than abc. As...Ch. 2.14 - Use a computer to find the three solutions of the...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Prob. 7PCh. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Find each of the following in the x+iy form and...Ch. 2.15 - Show that tan z never takes the values +1. Hint:...Ch. 2.15 - Show that tanh z never takes the values +1.Ch. 2.16 - Show that if the line through the origin and the...Ch. 2.16 - In each of the following problems, z represents...Ch. 2.16 - In each of the following problems, z represents...Ch. 2.16 - Z=(1+i)t-(2+i)(1-t). Hint: Show that the particle...Ch. 2.16 - z=z1t+z2(1t). Hint: See Problem 4; the straight...Ch. 2.16 - In electricity we learn that the resistance of two...Ch. 2.16 - In electricity we learn that the resistance of two...Ch. 2.16 - Find the impedance of the circuit in Figure 16.2...Ch. 2.16 - For the circuit in Figure 16.1: (a) Find in terms...Ch. 2.16 - Repeat Problem 9 for a circuit consisting of R, L,...Ch. 2.16 - Prove that...Ch. 2.16 - In optics, the following expression needs to be...Ch. 2.16 - Verify that eit, eit, cost, and sint satisfy...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Find one or more values of each of the following...Ch. 2.17 - Prob. 13MPCh. 2.17 - Find the disk of convergence of the series ...Ch. 2.17 - For what z is the series z1nn absolutely...Ch. 2.17 - Describe the set of points z for which Re(ei/2z)2.Ch. 2.17 - Verify the formulas in Problems 17 to 24....Ch. 2.17 - Verify the formulas in Problems 17 to 24....Ch. 2.17 - Verify the formulas in Problems 17 to 24....Ch. 2.17 - Verify the formulas in Problems 17 to 24....Ch. 2.17 - Verify the formulas in Problems 17 to 24....Ch. 2.17 - Verify the formulas in Problems 17 to 24....Ch. 2.17 - Verify the formulas in Problems 17 to 24....Ch. 2.17 - Verify the formulas in Problems 17 to 24....Ch. 2.17 - (a) Show that cosz=cosz. (b) Is sinz=sinz? (c) If...Ch. 2.17 - Find 2eiiiei+2. Hint: See equation (5.1).Ch. 2.17 - Show that Rez=12(z+z) and that Imz=(1/2i)(zz)....Ch. 2.17 - Evaluate the following absolute square of a...Ch. 2.17 - If z=ab and 1a+b=1a+1b, find z.Ch. 2.17 - Write the series for ex(1+i). Write 1+i in the rei...Ch. 2.17 - Show that if a sequence of complex numbers tends...Ch. 2.17 - Use a series you know to show that n=0(1+i)nn!=e.

Additional Math Textbook Solutions

Find more solutions based on key concepts
29-36. Total and Annual Returns. Compute the total and annual returns on the following investments. 29. Five ye...

Using & Understanding Mathematics: A Quantitative Reasoning Approach (7th Edition)

The equivalent expression of x(y+z) by using the commutative property.

Calculus for Business, Economics, Life Sciences, and Social Sciences (14th Edition)

Repeat problem P4-17 if VR=10 V and VL=20 V.

Introductory Mathematics for Engineering Applications

Solve the following trigonometric equations on the interval =[2,2] exactly. 322. 6cos2x3=0

Calculus Volume 1

Checkpoint1 Use the substitution method to solve this system: Answers to Checkpoint exercises are found at the...

Mathematics with Applications In the Management, Natural, and Social Sciences (12th Edition)

The table by using the given graph of h.

Calculus for Business, Economics, Life Sciences, and Social Sciences (13th Edition)

Knowledge Booster
Background pattern image
Math
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
Recommended textbooks for you
Text book image
Trigonometry (MindTap Course List)
Trigonometry
ISBN:9781305652224
Author:Charles P. McKeague, Mark D. Turner
Publisher:Cengage Learning
Text book image
Elementary Geometry For College Students, 7e
Geometry
ISBN:9781337614085
Author:Alexander, Daniel C.; Koeberlein, Geralyn M.
Publisher:Cengage,
Text book image
Algebra & Trigonometry with Analytic Geometry
Algebra
ISBN:9781133382119
Author:Swokowski
Publisher:Cengage
Text book image
College Algebra
Algebra
ISBN:9781305115545
Author:James Stewart, Lothar Redlin, Saleem Watson
Publisher:Cengage Learning
Text book image
Trigonometry (MindTap Course List)
Trigonometry
ISBN:9781337278461
Author:Ron Larson
Publisher:Cengage Learning
Text book image
Functions and Change: A Modeling Approach to Coll...
Algebra
ISBN:9781337111348
Author:Bruce Crauder, Benny Evans, Alan Noell
Publisher:Cengage Learning
SEE MORE TEXTBOOKS
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