21. Using Euler's formula, show that
Operations Research : Applications and Algorithms
4th Edition
ISBN:9780534380588
Author:Wayne L. Winston
Publisher:Wayne L. Winston
Chapter11: Nonlinear Programming
Section11.1: Review Of Differential Calculus
Problem 6P
Related questions
Question
21
![Therefore,
e't = C₁ cost + C₂ sin t
eir
for some constants c₁ and c₂. Why is this so?
c. Set t = 0 in equation (31) to show that C₁ = 1.
d. Assuming that equation (15) is true, differentiate
equation (31) and then set t = 0 to conclude that c₂ = i. Use the
values of c₁ and c₂ in equation (31) to arrive at Euler's formula.
21. Using Euler's formula, show that
eit + e-it
2
= cost,
eit - e-it
2i
= sin t.
22. If et is given by equation (14), show that e(+2) = e'¹¹ e 2¹
for any complex numbers r₁ and r2.
23. Consider the differential equation
ay" + by' + cy = 0,
where b² - 4ac < 0 and the characteristic equation has complex roots
A ±iu. Substitute the functions
u(t) = et cos(ut) and v(t) = et sin(ut)
for y in the differential equation and thereby confirm that they are
solutions.
24. If the functions y₁ and y2 are a fundamental set of solutions of
y" + p(t) y'+q(t) y = 0, show that between consecutive zeros of y₁
there is one and only one zero of y2. Note that this result is illustrated
by the solutions yi(t) = cost and y2(t) = sint of the equation
y" + y = 0.
27. 12y
28. 12y
29. 12y
30. 1²
31. 12.
Hint: Suppose that t₁ and t2 are two zeros of y₁ between which
there are no zeros of y2. Apply Rolle's theorem to y₁/2 to reach a
contradiction.
Change of Variables. Sometimes a differential equation with variable
coefficients,
32. In
enable e
coeffici
y" + p(t)y' +q(t) y = 0,
(32)
can be put in a more suitable form for finding a solution by making
a change of the independent variable. We explore these ideas in
Problems 25 through 36. In particular, in Problem 25 we show that
a class of equations known as Euler equations can be transformed
independent variable. Problems 26 through 31 ara
into equations with constant coefficients by a simple change of the
the new
specifie
a.
b.
C
I
t](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F1542aa1f-d598-4821-8ba3-9e5240803801%2Fb2178093-9834-42ee-95a1-bdd9a62c4622%2Fm1dho0n_processed.jpeg&w=3840&q=75)
Transcribed Image Text:Therefore,
e't = C₁ cost + C₂ sin t
eir
for some constants c₁ and c₂. Why is this so?
c. Set t = 0 in equation (31) to show that C₁ = 1.
d. Assuming that equation (15) is true, differentiate
equation (31) and then set t = 0 to conclude that c₂ = i. Use the
values of c₁ and c₂ in equation (31) to arrive at Euler's formula.
21. Using Euler's formula, show that
eit + e-it
2
= cost,
eit - e-it
2i
= sin t.
22. If et is given by equation (14), show that e(+2) = e'¹¹ e 2¹
for any complex numbers r₁ and r2.
23. Consider the differential equation
ay" + by' + cy = 0,
where b² - 4ac < 0 and the characteristic equation has complex roots
A ±iu. Substitute the functions
u(t) = et cos(ut) and v(t) = et sin(ut)
for y in the differential equation and thereby confirm that they are
solutions.
24. If the functions y₁ and y2 are a fundamental set of solutions of
y" + p(t) y'+q(t) y = 0, show that between consecutive zeros of y₁
there is one and only one zero of y2. Note that this result is illustrated
by the solutions yi(t) = cost and y2(t) = sint of the equation
y" + y = 0.
27. 12y
28. 12y
29. 12y
30. 1²
31. 12.
Hint: Suppose that t₁ and t2 are two zeros of y₁ between which
there are no zeros of y2. Apply Rolle's theorem to y₁/2 to reach a
contradiction.
Change of Variables. Sometimes a differential equation with variable
coefficients,
32. In
enable e
coeffici
y" + p(t)y' +q(t) y = 0,
(32)
can be put in a more suitable form for finding a solution by making
a change of the independent variable. We explore these ideas in
Problems 25 through 36. In particular, in Problem 25 we show that
a class of equations known as Euler equations can be transformed
independent variable. Problems 26 through 31 ara
into equations with constant coefficients by a simple change of the
the new
specifie
a.
b.
C
I
t
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