Chapter 7: Problem 13
Determine whether each equation represents direct, inverse, joint, or combined variation. $$ y=3 x z^{4} $$
Short Answer
Expert verified
Joint variation
Step by step solution
01
Identify the Variables
Identify the variables involved in the equation. Here, the variables are: \(y\), \(x\), and \(z\).
02
Analyze the Equation
Write the given equation. The equation is \(y = 3xz^4\).
03
Identify the Variation Type
Examine how the variables are related to one another. In the equation \(y = 3xz^4\), \(y\) is directly proportional to \(x\) and \(z^4\). There is no division of variables involved here.
04
Determine the Type of Variation
Since \(y\) changes based on the product of \(x\) and \(z^4\), it indicates a joint variation. Joint variation occurs when a variable depends on the product of two or more other variables.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
direct variation
Direct variation describes the relationship between two variables where one variable is a constant multiple of the other. Imagine you have a variable y and another variable x. In direct variation, as x increases, y increases proportionally, and as x decreases, y decreases proportionally. The formula for direct variation is given by the equation:
\( y = kx \),
where \( k \) is the constant of proportionality. Here are some key points about direct variation:
\( y = kx \),
where \( k \) is the constant of proportionality. Here are some key points about direct variation:
- The graph is a straight line passing through the origin.
- The ratio \( \frac{y}{x} \) is always constant.
- If you double x, y will also double if they vary directly.
inverse variation
Inverse variation occurs when one variable increases while the other decreases such that their product is constant. In mathematical terms, if y varies inversely as x, the relationship is defined by the equation:
\( y = \frac{k}{x} \),
where \( k \) is the constant of inverse variation. Some important features of inverse variation include:
\( y = \frac{k}{x} \),
where \( k \) is the constant of inverse variation. Some important features of inverse variation include:
- The product \( xy \) is always constant.
- The graph of inverse variation is a hyperbola.
proportionality
Proportionality covers both direct and inverse variation. It is the concept that two quantities change in a dependent manner. When dealing with direct proportionality, as one quantity increases, the other also increases at a constant rate.
In the case of inverse proportionality, as one quantity increases, the other decreases, and their product remains constant. The equations for proportionality are:
In the case of inverse proportionality, as one quantity increases, the other decreases, and their product remains constant. The equations for proportionality are:
- For direct proportionality: \( y = kx \)
- For inverse proportionality: \( y = \frac{k}{x} \)
product of variables
The product of variables plays a crucial role in understanding different types of variation, including joint variation. Joint variation is when a variable depends on the product of two or more variables. For example, in the equation \( y = 3xz^4 \), you can see that y changes based on the product of x and \(z^4\). The important features to note here are:
- Several variables multiply together to affect the outcome.
- There is no division involved; it only involves multiplication.
- The constant 3 in \( y = 3xz^4 \) indicates how much y changes for a unit change in the product of x and \( z^4 \).