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# One to one functions

- Intro Lesson14:50
- Lesson: 13:20
- Lesson: 22:56
- Lesson: 32:37

### One to one functions

#### Lessons

$\bullet$ To determine if an expression is a function, we perform the vertical line test.

$\bullet$ Surjective/Onto: For every $y$ value, there exists at least one $x$ value.

$\bullet$ Injective/Into/one-to-one: For every $y$ value, there exists at most one $x$ value.

$\bullet$ To determine if a function is one-to-one, we perform the horizontal line test.

- IntroductionIntroduction to one to one functions
i. Review: How are functions, Surjective functions and Injective functions related?

ii. How to determine if an expression is a function?

iii. What are Surjective functions?

iv. What are one to one functions?

- 1.
**Discussing the Differences Between Surjective and Injective Functions**Identify the differences between Surjective and Injective functions and give an example for each of the functions.

- 2.
**Identifying One-to-One Functions On a Graph**Learning the Horizontal Line Test and understanding how it can be implemented to identify one-to-one functions on a graph.

- 3.
**Applying the Horizontal Line Test**Determine if the following graphs are one-to-one functions using the horizontal line test.

i.

ii.

iii.

iv.