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Intermediate Value Theorem: locating a root practice problems
Use the Intermediate Value Theorem to show a root exists in an interval, then narrow it by bisection. 58 problems with worked solutions; in 58 of them every
equation is proved by a computer algebra system.
16 worked problems
Try each one before opening the solution. Every line is labeled with what checked it. How we verify
Show that \( \displaystyle x + e^{x} - 5 = 0 \) has a solution in \( \displaystyle [1, 2] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [1, 2] (it is built from continuous functions), so the IVT applies.
Reviewed
\[ \left. x + e^{x} - 5 \right|_{\substack{ x=1 }} = -4 + e \]
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle - x + \cos{\left(x \right)} = 0 \) has a solution in \( \displaystyle [0, 1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [0, 1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{5} + x^{2} - 5 = 0 \) has a solution in \( \displaystyle [1, 2] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [1, 2] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} - 3 = 0 \) has a solution in \( \displaystyle [1, 2] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [1, 2] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} - 3 x - 1 = 0 \) has a solution in \( \displaystyle [-2, -1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [-2, -1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{4} + x - 5 = 0 \) has a solution in \( \displaystyle [-2, -1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [-2, -1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} - 3 x = 0 \) has a solution in \( \displaystyle [-2, -1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [-2, -1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} + 2 x - 1 = 0 \) has a solution in \( \displaystyle [0, 1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [0, 1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} - x - 3 = 0 \) has a solution in \( \displaystyle [1, 2] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [1, 2] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} + x - 1 = 0 \) has a solution in \( \displaystyle [0, 1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [0, 1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} - x + 2 = 0 \) has a solution in \( \displaystyle [-2, -1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [-2, -1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} + 3 x + 3 = 0 \) has a solution in \( \displaystyle [-1, 0] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [-1, 0] (it is built from continuous functions), so the IVT applies.
The sign changes on [-1, -3/4], so a root lies there.
Reviewed
Answer \( \left[-1, - \frac{3}{4}\right] \)
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} - 2 x + 1 = 0 \) has a solution in \( \displaystyle [-2, -1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [-2, -1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} + 3 x + 6 = 0 \) has a solution in \( \displaystyle [-2, -1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [-2, -1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} + x + 5 = 0 \) has a solution in \( \displaystyle [-2, -1] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [-2, -1] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
Show that \( \displaystyle x^{3} - 3 x - 6 = 0 \) has a solution in \( \displaystyle [2, 3] \), then use two steps of bisection to find an interval of length \( \displaystyle \tfrac14 \) containing it.
f is continuous on [2, 3] (it is built from continuous functions), so the IVT applies.
✓ Nihil obstat Lines: 4 proved, 2 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
More intermediate value theorem: locating a root practice