Chapter 2: Problem 8
Determine in each exercise whether or not the function is homogeneous. If it is homogeneous, state the degree of the function. $$ \tan \frac{3 y}{x} $$.
Short Answer
Expert verified
The function is homogeneous of degree 0.
Step by step solution
01
Identify Function and Variables
We are given the function \( f(x, y) = \tan\left(\frac{3y}{x}\right) \). Note that the variables here are \( x \) and \( y \). Homogeneity of a function is determined with respect to these variables.
02
Define Homogeneous Function
A function \( f(x, y) \) is homogeneous of degree \( n \) if for all \( t \in \mathbb{R} \), \( f(tx, ty) = t^n f(x, y) \). We will test this definition on the given function.
03
Substitute Scaled Variables
Substitute \( x = tx \) and \( y = ty \) in the given function: \[f(tx, ty) = \tan\left(\frac{3(ty)}{tx}\right) = \tan\left(\frac{3ty}{tx}\right) = \tan\left(\frac{3y}{x}\right) = f(x, y)\].
04
Analyze the Results
The function remains unchanged after scaling, i.e., \( f(tx, ty) = f(x, y) \). This implies that \( n = 0 \), and the function is homogeneous of degree 0.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Degree of a Function
In mathematics, the degree of a function is a critical concept when studying homogeneous functions. A function is considered homogeneous if scaling all its input variables by a constant factor results in the output being scaled by a constant factor raised to a power, typically denoted by the degree. The degree gives insight into how the function behaves when its inputs are scaled.
For a multivariable function, such as \( f(x, y) \), the degree \( n \) is determined by evaluating whether \( f(tx, ty) = t^n f(x, y) \). If this is true for any real number \( t \), the function is homogeneous of degree \( n \).
In the case of the function \( \tan\left(\frac{3y}{x}\right) \), when we consider scaling \( x \) and \( y \) by \( t \), the function remains unchanged (\( n = 0 \)). Thus, the degree of this homogeneous function is 0.
For a multivariable function, such as \( f(x, y) \), the degree \( n \) is determined by evaluating whether \( f(tx, ty) = t^n f(x, y) \). If this is true for any real number \( t \), the function is homogeneous of degree \( n \).
In the case of the function \( \tan\left(\frac{3y}{x}\right) \), when we consider scaling \( x \) and \( y \) by \( t \), the function remains unchanged (\( n = 0 \)). Thus, the degree of this homogeneous function is 0.
Scaling Variables
Scaling variables is a process in which each variable of a function is multiplied by a constant factor. This process is essential for determining if a function is homogeneous.
Let's look at how this applies to \( f(x, y) = \tan\left(\frac{3y}{x}\right) \). When we substitute \( x = tx \) and \( y = ty \), we get \( f(tx, ty) = \tan\left(\frac{3ty}{tx}\right) \). Simply observing the scaled variables, it becomes clear that any factor \( t \) cancels out, leaving the original function \( f(x, y) \) unchanged.
This invariance under scaling is a hallmark of homogeneous functions, indicating they respond predictably to changes in the inputs.
Let's look at how this applies to \( f(x, y) = \tan\left(\frac{3y}{x}\right) \). When we substitute \( x = tx \) and \( y = ty \), we get \( f(tx, ty) = \tan\left(\frac{3ty}{tx}\right) \). Simply observing the scaled variables, it becomes clear that any factor \( t \) cancels out, leaving the original function \( f(x, y) \) unchanged.
This invariance under scaling is a hallmark of homogeneous functions, indicating they respond predictably to changes in the inputs.
Identifying Homogeneous Functions
Identifying whether a function is homogeneous involves checking if its form remains constant under a uniform scaling of its variables. A function \( f(x, y) \) is homogeneous of a certain degree if, when substituting each variable \( x_i \) with \( tx_i \), there exists a degree \( n \) such that \( f(tx, ty) = t^n f(x, y) \) holds true.
For example, take the function \( \tan\left(\frac{3y}{x}\right) \). Upon performing the scaling step, the function \( \tan\left(\frac{3ty}{tx}\right) = \tan\left(\frac{3y}{x}\right) \) indicates it is homogeneous with a degree of 0. This results because the function does not change when both \( x \) and \( y \) are scaled by the same factor, showing no dependence on \( t \).
For example, take the function \( \tan\left(\frac{3y}{x}\right) \). Upon performing the scaling step, the function \( \tan\left(\frac{3ty}{tx}\right) = \tan\left(\frac{3y}{x}\right) \) indicates it is homogeneous with a degree of 0. This results because the function does not change when both \( x \) and \( y \) are scaled by the same factor, showing no dependence on \( t \).
Mathematical Problem Solving
Mathematical problem-solving often relies on identifying the properties of functions, such as homogeneity. Recognizing these properties can simplify complex problems significantly.
Understanding whether a function is homogeneous helps in scenarios where variables change continuously or discretely. It implies a uniform property enabling shortcuts in solving mathematical equations.
Understanding whether a function is homogeneous helps in scenarios where variables change continuously or discretely. It implies a uniform property enabling shortcuts in solving mathematical equations.
- Firstly, rewrite the function with scaled variables.
- Next, compare the scaled function to the original function.
- If they are equivalent, you've identified a homogeneous function!