The function y = x is its own inverse?

In summary, the function y = x is its own inverse because it is the same when you swap the coordinates within each pair.
  • #1
eleventhxhour
74
0
The function y = x is its own inverse. Why?
 
Mathematics news on Phys.org
  • #2
To answer this question you need to know the definition of the inverse function (in general). Do you belong to the set of people who have this knowledge?
 
  • #3
Evgeny.Makarov said:
To answer this question you need to know the definition of the inverse function (in general). Do you belong to the set of people who have this knowledge?

Yup, I know what an inverse function is. I just don't understand how it can be its own inverse
 
  • #4
eleventhxhour said:
The function y = x is its own inverse. Why?

A trivial explanation of that is $\displaystyle y = x \implies x = y$. Also the function $\displaystyle y= \frac{1}{x}$ is its own inverse because $\displaystyle y = \frac{1}{x} \implies x= \frac{1}{y}$. Other functions don't have this property, for example $\displaystyle y= x^{2} \implies x = \sqrt{y}$... Kind regards $\chi$ $\sigma$
 
  • #5
eleventhxhour said:
Yup, I know what an inverse function is. I just don't understand how it can be its own inverse
Let's see the definition that you are using and we'll determine if $y=x$ fits it.
 
  • #6
Evgeny.Makarov said:
Let's see the definition that you are using and we'll determine if $y=x$ fits it.

The inverse of a function is a relation formed by interchanging the coordinates within each ordered pair of the original function.
 
  • #7
Great. Let's assume that the domain and codomain of the function $y=x$ are $D$. Then the function is $\{(x,x)\mid x\in D\}$. Obviously, if you swap the elements of each pair, you get the same set since each pair does not change.
 
  • #8
Evgeny.Makarov said:
Great. Let's assume that the domain and codomain of the function $y=x$ are $D$. Then the function is $\{(x,x)\mid x\in D\}$. Obviously, if you swap the elements of each pair, you get the same set since each pair does not change.

Ohh, okay. That makes sense. Thanks! (:
 

FAQ: The function y = x is its own inverse?

What is the function y = x?

The function y = x is a mathematical equation that represents a straight line passing through the origin with a slope of 1.

What does it mean for a function to be its own inverse?

A function is its own inverse if the output of the function is the same as the input when the function is applied twice. In other words, if the function is applied to its own output, the result will be the original input.

How can you prove that y = x is its own inverse?

To prove that y = x is its own inverse, you can use the property of inverse functions, which states that if f and g are inverse functions, then f(g(x)) = x and g(f(x)) = x. In this case, f(x) = y = x, and g(x) = x, so both f(g(x)) and g(f(x)) will equal x, proving that y = x is its own inverse.

What is the graph of y = x?

The graph of y = x is a straight line passing through the origin and extending infinitely in both the positive and negative directions. It has a slope of 1 and intersects the x-axis and y-axis at the point (0,0).

How is the function y = x its own inverse useful in mathematics?

The function y = x being its own inverse has various applications in mathematics. It is used in solving equations, finding the inverse of a matrix, and in geometry to reflect points across the line y = x. It is also an important concept in abstract algebra and functional analysis.

Similar threads

Back
Top