Solve the variation problems in Exercises 77–82. The pitch of a musical tone varies inversely as its wavelength. A tone has a pitch of 660 vibrations per second and a wavelength of 1.6 feet. What is the pitch of a tone that has a wavelength of 2.4 feet?
Table of contents
- 0. Review of Algebra4h 18m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations1h 43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 5m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 22m
- 10. Combinatorics & Probability1h 45m
1. Equations & Inequalities
Rational Equations
Problem 25
Textbook Question
Write each formula as an English phrase using the word varies or proportional. V = 1/3 πr2h, where V is the volume of a cone of radius r and height h
Verified step by step guidance1
Identify the variables in the formula: \(V\) represents the volume of the cone, \(r\) is the radius, and \(h\) is the height.
Recognize the constants and coefficients in the formula: \(\frac{1}{3}\) and \(\pi\) are constants that do not change with \(r\) or \(h\).
Observe how \(V\) depends on \(r\) and \(h\): \(V\) is multiplied by \(r^2\) and \(h\), indicating that \(V\) varies with both \(r^2\) and \(h\).
Express the relationship using the word 'varies' or 'proportional': Since \(V\) is equal to a constant times \(r^2\) times \(h\), we say that \(V\) varies jointly as the square of the radius and the height.
Write the English phrase: 'The volume \(V\) of a cone varies jointly as the square of its radius \(r\) and its height \(h\).'
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Direct Variation
Direct variation describes a relationship where one quantity changes proportionally with another. If y varies directly as x, then y = kx for some constant k. In the formula for volume, understanding which variables increase or decrease together helps express the relationship using 'varies' or 'proportional'.
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Volume of a Cone Formula
The volume of a cone is given by V = (1/3)πr²h, where r is the radius and h is the height. This formula shows how volume depends on both the square of the radius and the height, indicating that volume changes with these dimensions. Recognizing this helps translate the formula into a verbal proportional relationship.
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Translating Mathematical Expressions into Words
Translating formulas into English involves expressing mathematical relationships clearly using terms like 'varies directly' or 'is proportional to'. This skill requires identifying constants and variables and describing how one quantity depends on others, which aids in understanding and communicating algebraic relationships.
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