Definition:
A function is a way to connect two sets of values, where each input (from the first set, called the domain) gives exactly one output (from the second set, called the codomain).
Types of Functions:
- Linear Functions: Form a straight line and have a constant rate of change.
- Quadratic Functions: Create a U-shaped graph (parabolic).
- Exponential Functions: Describe processes of growth or decay.
- Periodic Functions: Repeat their values at regular intervals, like sine and cosine.
Domain and Range:
- Domain: All possible input values (x-values) for the function.
- Range: All possible output values (y-values) the function can produce.
Evaluating Functions:
To find out the output for a specific input, replace the input in the function’s equation. For example, if you have a function and want to evaluate it at a certain point, you plug in that point to get the output.
Composite Functions:
A composite function is made by combining two functions to create a new, more complex function.
Inverse Functions:
An inverse function reverses the original function. If you apply the original function and then its inverse, you go back to where you started. Not all functions have inverses.
Continuity and Discontinuity:
A function is continuous if its graph has no breaks or jumps. Discontinuities can be "removable" (like a hole in the graph) or "non-removable" (like an actual jump).
Symmetry:
Functions can show symmetry. Even functions are symmetric about the y-axis, while odd functions are symmetric about the origin.
Evaluating and Comparing Relationships:
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Graphing Functions: The graph shows how the function behaves and the relationship between input and output. Important parts include where it crosses the axes, its slope, and its shape.
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Slope and Rate of Change: The slope tells you how steep a linear function is, which can relate to speed or growth rate.
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Finding Solutions: You can solve functions by graphing (finding where two graphs intersect) or solving algebraically (setting them equal and solving for x).
Modeling Real-World Phenomena:
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Applications of Functions: Functions can be used to describe real-life situations in areas like science, economics, and engineering. Examples include:
- Population Growth: Exponential functions show how populations grow.
- Projectile Motion: Quadratic functions describe the flight of objects under gravity.
- Supply and Demand: Linear functions can model how supply changes with price.
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Data Fitting: Functions help match curves to real data, making predictions about trends.
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Simulation: Functions can model complex systems over time to understand how they behave.
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Optimization: Functions are used to find the best solutions for problems, like maximizing resource use or setting prices.