Condition for a function to be injective

In summary, a function is injective if each input corresponds to a unique output, and no two different inputs can result in the same output. To check if a function is injective, we can use the horizontal line test or use algebra to show that no two different inputs can result in the same output. The condition for a function to be injective is that different inputs must have different outputs. A function can be both injective and surjective, and this is called a bijective function. Injective functions have important applications in cryptography, computer science, and data analysis, and are essential in solving mathematical problems involving inverses.
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Homework Statement


Do all the preimages on X need to have a (and of course I know only one but) image in Y for the f:x->y to be injective?
IS THE FOLLOWING FUNCTION INJECTIVE SINCE ONE ELEMENT OF FIRST DOES NOT HAVE ANY IMAGE
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The Attempt at a Solution


Thank You.
 

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  • #2
The way you have shown it, f is not a function from X to Y.
 
  • #3
Thank you.
 

1. What does it mean for a function to be injective?

A function is said to be injective if each input (domain element) corresponds to a unique output (range element). This means that no two different input values can result in the same output value.

2. How do you check if a function is injective?

To check if a function is injective, we can use the horizontal line test. This involves drawing a horizontal line on the graph of the function and checking if the line intersects the graph at more than one point. If it does, then the function is not injective. Another method is to use algebra to show that no two different input values can result in the same output value.

3. What is the condition for a function to be injective?

The condition for a function to be injective is that for any two different input values, the corresponding output values must be different. In other words, the function cannot map different inputs to the same output.

4. Can a function be both injective and surjective?

Yes, a function can be both injective and surjective. A function that is both injective and surjective is called a bijective function. This means that each input has a unique output and every output has a corresponding input.

5. What is the importance of injective functions in mathematics?

Injective functions have several important applications in mathematics, including in cryptography, computer science, and data analysis. They also play a crucial role in determining the inverse of a function, which is essential in solving many mathematical problems.

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