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Second-order initial and boundary value problems practice problems
Constant-coefficient second-order equations with initial or boundary conditions. 60 problems with worked solutions; in 60 of them every
equation is proved by a computer algebra system.
11 worked problems
Try each one before opening the solution. Every line is labeled with what checked it. How we verify
The characteristic equation has complex roots 2 ± 2i.✓ Proved
So y = C₁exp(2*x)*cos(2*x) + C₂exp(2*x)*sin(2*x); the two conditions fix C₁ and C₂.
Reviewed
\[ 8 \left(\sin{\left(2 x \right)} - 3 e^{\frac{\pi}{2}} \cos{\left(2 x \right)}\right) e^{2 x - \frac{\pi}{2}} - 4 \frac{d}{d x} \left(\sin{\left(2 x \right)} - 3 e^{\frac{\pi}{2}} \cos{\left(2 x \right)}\right) e^{2 x - \frac{\pi}{2}} + \frac{d^{2}}{d x^{2}} \left(\sin{\left(2 x \right)} - 3 e^{\frac{\pi}{2}} \cos{\left(2 x \right)}\right) e^{2 x - \frac{\pi}{2}} = 0 \]
It satisfies the equation ...✓ Proved
\[ \left. \left(\sin{\left(2 x \right)} - 3 e^{\frac{\pi}{2}} \cos{\left(2 x \right)}\right) e^{2 x - \frac{\pi}{2}} \right|_{\substack{ x=0 }} = -3 \]
... y(0) = -3 ...✓ Proved
\[ \left. \left(\sin{\left(2 x \right)} - 3 e^{\frac{\pi}{2}} \cos{\left(2 x \right)}\right) e^{2 x - \frac{\pi}{2}} \right|_{\substack{ x=\frac{\pi}{4} }} = 1 \]
y(pi/4) = 1.✓ Proved
Answer \( y = \left(\sin{\left(2 x \right)} - 3 e^{\frac{\pi}{2}} \cos{\left(2 x \right)}\right) e^{2 x - \frac{\pi}{2}} \)
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
The characteristic equation has a repeated root 1.✓ Proved
So y = C₁exp(x) + C₂x*exp(x); the two conditions fix C₁ and C₂.
Reviewed
\[ \left(- 4 e x + 2 x + 4 e\right) e^{x - 1} - 2 \frac{d}{d x} \left(- 4 e x + 2 x + 4 e\right) e^{x - 1} + \frac{d^{2}}{d x^{2}} \left(- 4 e x + 2 x + 4 e\right) e^{x - 1} = 0 \]
It satisfies the equation ...✓ Proved
\[ \left. 2 \left(- 2 e x + x + 2 e\right) e^{x - 1} \right|_{\substack{ x=0 }} = 4 \]
... y(0) = 4 ...✓ Proved
\[ \left. 2 \left(- 2 e x + x + 2 e\right) e^{x - 1} \right|_{\substack{ x=1 }} = 2 \]
y(1) = 2.✓ Proved
Answer \( y = 2 \left(- 2 e x + x + 2 e\right) e^{x - 1} \)
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
Answer \( y = \frac{3 \left(e \sin{\left(3 x \right)} - \sin{\left(3 x - 3 \right)}\right) e^{- x}}{\sin{\left(3 \right)}} \)
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
The characteristic equation has complex roots 2 ± 4i.✓ Proved
So y = C₁exp(2*x)*cos(4*x) + C₂exp(2*x)*sin(4*x); the two conditions fix C₁ and C₂.
Reviewed
\[ \frac{20 \left(- 3 \sin{\left(4 x \right)} + 2 e^{2} \sin{\left(4 x - 4 \right)}\right) e^{2 x - 2}}{\sin{\left(4 \right)}} - 4 \frac{d}{d x} \frac{\left(- 3 \sin{\left(4 x \right)} + 2 e^{2} \sin{\left(4 x - 4 \right)}\right) e^{2 x - 2}}{\sin{\left(4 \right)}} + \frac{d^{2}}{d x^{2}} \frac{\left(- 3 \sin{\left(4 x \right)} + 2 e^{2} \sin{\left(4 x - 4 \right)}\right) e^{2 x - 2}}{\sin{\left(4 \right)}} = 0 \]
It satisfies the equation ...✓ Proved
\[ \left. \frac{\left(- 3 \sin{\left(4 x \right)} + 2 e^{2} \sin{\left(4 x - 4 \right)}\right) e^{2 x - 2}}{\sin{\left(4 \right)}} \right|_{\substack{ x=0 }} = -2 \]
... y(0) = -2 ...✓ Proved
\[ \left. \frac{\left(- 3 \sin{\left(4 x \right)} + 2 e^{2} \sin{\left(4 x - 4 \right)}\right) e^{2 x - 2}}{\sin{\left(4 \right)}} \right|_{\substack{ x=1 }} = -3 \]
y(1) = -3.✓ Proved
Answer \( y = \frac{\left(- 3 \sin{\left(4 x \right)} + 2 e^{2} \sin{\left(4 x - 4 \right)}\right) e^{2 x - 2}}{\sin{\left(4 \right)}} \)
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
✓ Nihil obstat Lines: 4 proved, 1 reviewed. The answer was also checked a second way, without looking at the solution. Reviewers found nothing wrong with the explanation. The full receipt ·
How we verify
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