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Ch. 1 - Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077당신이 사용하는 게 아니라요?교과서 변경
1장, 문제 1.1.65

Theory and Examples


The variables r and s are inversely proportional, and r = 6 when s = 4. Determine s when r = 10.

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Understand the concept of inverse proportionality: If two variables r and s are inversely proportional, it means that as one increases, the other decreases in such a way that their product remains constant. Mathematically, this relationship can be expressed as r * s = k, where k is a constant.
Use the given values to find the constant k: We know that r = 6 when s = 4. Substitute these values into the equation r * s = k to find k. This gives us 6 * 4 = k, so k = 24.
Set up the equation for the new condition: We need to find s when r = 10. Using the inverse proportionality relationship, substitute r = 10 into the equation r * s = k, which becomes 10 * s = 24.
Solve for s: To find the value of s, divide both sides of the equation 10 * s = 24 by 10. This gives s = 24 / 10.
Simplify the expression: Simplify the fraction 24 / 10 to find the value of s. This can be done by dividing the numerator and the denominator by their greatest common divisor.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Inverse Proportionality

Inverse proportionality means that as one variable increases, the other decreases in such a way that their product remains constant. In mathematical terms, if r and s are inversely proportional, then r * s = k, where k is a constant. This relationship allows us to find the value of one variable when the other is known.
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4:49
Inverse Cosine

Finding the Constant of Proportionality

To solve problems involving inverse proportionality, we first need to determine the constant of proportionality (k). This is done by substituting the known values of r and s into the equation r * s = k. For example, with r = 6 and s = 4, we calculate k = 6 * 4 = 24, which will be used to find other values.
추천 영상:
01:56
Finding Limits by Direct Substitution Example 1

Solving for Unknown Variables

Once we have the constant of proportionality, we can solve for unknown variables by rearranging the equation. For instance, if we want to find s when r = 10, we set up the equation 10 * s = k. By substituting k = 24, we can solve for s, leading to s = 24 / 10 = 2.4.
추천 영상:
04:27
Substitution With an Extra Variable