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Exemplo 8.92 de Elementary Algebra, 8.9 Use Direct and Inverse Variation
Use Direct and Inverse Variation: exemplo 8.92
Problema e solução em inglês, como no livro original.
The frequency of a guitar string varies inversely with its length. A 26” long string has a frequency of 440 vibrations per second.
- ⓐ Write the equation of variation.
- ⓑ How many vibrations per second will there be if the string’s length is reduced to 20” by putting a finger on a fret?
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Solução
ⓐ
The frequency varies inversely with the length. Name the variables. Let frequency.
lengthWrite the formula for inverse variation. We will use in place of and in place of . Substitute the given values for the variables. Solve for the constant of variation. Write the equation that relates and . Substitute in the constant of variation. ⓑ
Sua vez
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The number of hours it takes for ice to melt varies inversely with the air temperature. Suppose a block of ice melts in 2 hours when the temperature is 65 degrees.
- ⓐ Write the equation of variation.
- ⓑ How many hours would it take for the same block of ice to melt if the temperature was 78 degrees?
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