Chapter 5: Problem 19
For the following exercises, write an equation describing the relationship of the given variables. \(y\) varies jointly as \(x\) and the square root of \(z\) and when \(x=2\) and \(z=25,\) then \(y=100\).
Short Answer
Expert verified
The equation is \( y = 10x \sqrt{z} \).
Step by step solution
01
Understand the Joint Variation
When a variable varies jointly with other variables, it means that it is directly proportional to the product of those variables. In this case, \( y \) varies jointly as \( x \) and the square root of \( z \), which means we can write this relationship as \( y = kx \sqrt{z} \), where \( k \) is the constant of proportionality.
02
Substitute Given Values to Find \( k \)
We know \( y = 100 \), \( x = 2 \), and \( z = 25 \). Substitute these values into the equation \( y = kx \sqrt{z} \) to find \( k \). \[ 100 = k \times 2 \times \sqrt{25} \] Simplifying the square root, \( \sqrt{25} = 5 \), so: \[ 100 = k \times 2 \times 5 \] \[ 100 = 10k \].
03
Solve for \( k \)
Now divide both sides of the equation by 10 to solve for \( k \): \[ k = \frac{100}{10} \] \[ k = 10 \].
04
Write the Equation
Now that we have found \( k = 10 \), substitute \( k \) back into the relationship to formulate the complete equation: \[ y = 10x \sqrt{z} \]. This equation describes \( y \) as it varies jointly with \( x \) and the square root of \( z \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Constant of Proportionality
When dealing with variations, the **constant of proportionality** is a critical factor that connects the relationship between variables. It helps indicate how much one variable changes concerning others. In our example, the constant of proportionality, denoted by **k**, shows how the variable **y** varies in response to changes in **x** and the square root of **z**.
To find the constant of proportionality, we use given specific values to solve for **k**. In this exercise, when given values are substituted into the joint variation equation \( y = kx \sqrt{z} \), we used \( y = 100, x = 2, \text{ and } z = 25 \) to determine \( k \). Hence, \( k \) = 10 in this case.
To find the constant of proportionality, we use given specific values to solve for **k**. In this exercise, when given values are substituted into the joint variation equation \( y = kx \sqrt{z} \), we used \( y = 100, x = 2, \text{ and } z = 25 \) to determine \( k \). Hence, \( k \) = 10 in this case.
- **Proportionality** indicates a stable relationship.
- **Constant** implies it does not change with these specific conditions.
- We use it to predict other variables' behavior consistently.
Direct Variation
Understanding **direct variation** is vital in many algebraic relationships. This concept signifies that two variables increase or decrease proportionally, at a steady rate. It means when one variable increases, the other follows suit. You can describe it with equations like \( y = kx \), showing a direct link.
In the context of this problem, starting with the equation \( y = kx \sqrt{z} \), the variable **y** increases directly as \( x \) and the square root of **z** increase. Here, our task is to see how changes in \( x \) and \( z \) directly affect **y**.
In the context of this problem, starting with the equation \( y = kx \sqrt{z} \), the variable **y** increases directly as \( x \) and the square root of **z** increase. Here, our task is to see how changes in \( x \) and \( z \) directly affect **y**.
- Summarized as linear and straightforward.
- Chained together by a **constant (k)**.
- Predictability in one variable from another's change.
Square Root
Unraveling the **square root** concept deals with understanding the fundamental operation of finding a number that, when multiplied by itself, returns the original value. For instance, the square root of 25 is 5 because \( 5 \times 5 = 25 \).
In the given exercise, the square root of **z** plays a part in how **y** varies with both **x** and \( \sqrt{z} \). By taking the square root of **z**, we modify how substantially **z** contributes to the outcome. It is crucial for balancing the equation and understanding how **z** influences **y**.
In the given exercise, the square root of **z** plays a part in how **y** varies with both **x** and \( \sqrt{z} \). By taking the square root of **z**, we modify how substantially **z** contributes to the outcome. It is crucial for balancing the equation and understanding how **z** influences **y**.
- Provides a way to simplify complex relationships.
- Alters how much a variable contributes to the solution.
- Key in reducing or balancing in multi-variable scenarios.
Algebraic Equation
An **algebraic equation** represents mathematical relationships using symbols and numbers. In these equations, equality is expressed through one or more variables.
In this context, the algebraic equation provided is **\( y = kx \sqrt{z} \)**. It describes a joint variation where changes in **x** and \( \sqrt{z} \) lead to changes in **y**. Each component plays a specific role in solving the equation, ensuring both sides equal as alterations in the variables control the outcome. Finding **k** solidifies the relationship, making the equation both specific and useful.
In this context, the algebraic equation provided is **\( y = kx \sqrt{z} \)**. It describes a joint variation where changes in **x** and \( \sqrt{z} \) lead to changes in **y**. Each component plays a specific role in solving the equation, ensuring both sides equal as alterations in the variables control the outcome. Finding **k** solidifies the relationship, making the equation both specific and useful.
- Serves as a structured mathematical statement.
- Important in expressing predictable behavior in varied conditions.
- Ensures logical solutions for diverse problems.