 # Determining the Key Features of Function Graphs

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Determining the Key Features of Function Graphs

The Key Features of Function Graphs - Preview
Domain and Range x-intercepts and y-intercepts Intervals of increasing, decreasing, and constant behavior Parent Equations Maxima and Minima

Domain Domain is the set of all possible input or x-values
To find the domain of the graph we look at the x-axis of the graph

Determining Domain - Symbols
Open Circle → Exclusive ( ) Closed Circle → Inclusive [ ]

Identifying the Domain
Start at the far left of the graph. Move along the x-axis until you find the lowest possible x-value of the graph. This is your lower bound. Note if you have a open circle or a closed circle. Keep moving along the x-axis until you find your highest possible x-value of the graph. This is your upper bound. Note if you have a open circle or a closed circle.

Examples Domain: Domain:

Example Domain:

Determining Domain - Infinity

Examples Domain: Domain:

Your Turn: Complete problems 3, 7, and find the domain of 9 and 10 on pg. 160 from the Xeroxed sheets

Range The set of all possible output or y-values
To find the range of the graph we look at the y-axis of the graph We also use open and closed circles for the range

Identifying the Range Start at the far left of the graph.
Move along the x-axis until you find the lowest possible x-value of the graph. This is your lower bound. Note if you have a open circle or a closed circle. Keep moving along the x-axis until you find your highest possible x-value of the graph. This is your upper bound. Note if you have a open circle or a closed circle.

Examples Range: Range:

Examples Range: Range:

Your Turn: Complete problems 4, 8, and find the range of 9 and 10 on pg. 160 from the Xeroxed sheets

X-Intercepts Where the graph crosses the x-axis Has many names:
Roots Zeros

Examples x-intercepts: x-intercepts:

Y-Intercepts Where the graph crosses the y-axis y-intercepts:

Seek and Solve!!!

Types of Function Behavior
Increasing Decreasing Constant When determining the type of behavior, we always move from left to right on the graph

Roller Coasters!!! Fujiyama in Japan

Types of Behavior – Increasing
As x increases, y also increases Direct Relationship

Types of Behavior – Constant
As x increases, y stays the same

Types of Behavior – Decreasing
As x increases, y decreases Inverse Relationship

Identifying Intervals of Behavior
We use interval notation The interval measures x-values. The type of behavior describes y-values. Increasing: [0, 4) The y-values are increasing the x-values are between 0 inclusive and 4 exclusive when

Identifying Intervals of Behavior
Increasing: Constant: Decreasing: x 1 1

Identifying Intervals of Behavior, cont.
Increasing: Constant: Decreasing: x -3 -1 Don’t get distracted by the arrows! Even though both of the arrows point “up”, the graph isn’t increasing at both ends of the graph!

Your Turn: Complete problems 1 – 4 on The Key Features of Function Graphs – Part II handout.

1. 2. 3. 4.

What do you think of when you hear the word parent?

Parent Function The most basic form of a type of function
Determines the general shape of the graph

Basic Types of Parent Functions
Linear Absolute Value Greatest Integer Quadratic Cubic Square Root Cube Root Reciprocal

Parent Function Flipbook

Function Name: Linear Parent Function: f(x) = x “Baby” Functions: y 2

Greatest Integer Function
f(x) = [[x]] f(x) = int(x) Rounding function Always round down

“Baby” Functions Look and behave similarly to their parent functions
To get a “baby” functions, add, subtract, multiply, and/or divide parent equations by (generally) constants f(x) = x2 f(x) = 5x2 – 14 f(x) = f(x) = f(x) = x3 f(x) = -2x3 + 4x2 – x + 2

“Baby” Functions, cont. f(x) = |x|

Identifying Parent Functions
From Equations: Identify the most important operation Special Operation (absolute value, greatest integer) Division by x Highest Exponent (this includes square roots and cube roots)

Examples f(x) = x3 + 4x – 3 f(x) = -2| x | + 11

Identifying Parent Equations
From Graphs: Try to match graphs to the closest parent function graph

Examples

Your Turn: Complete problems 5 – 12 on The Key Features of Function Graphs handout

Maximum (Maxima) and Minimum (Minima) Points
Peaks (or hills) are your maximum points Valleys are your minimum points

Identifying Minimum and Maximum Points
Write the answers as points You can have any combination of min and max points Minimum: Maximum:

Examples

Your Turn: Complete problems 1 – 6 on The Key Features of Function Graphs – Part III handout.

Reminder: Find f(#) and Find f(x) = x
Find the value of f(x) when x equals #. Solve for f(x) or y! Find f(x) = # Find the value of x when f(x) equals #. Solve for x!

Evaluating Graphs of Functions – Find f(#)
Draw a (vertical) line at x = # The intersection points are points where the graph = f(#) f(1) = f(–2) =

Evaluating Graphs of Functions – Find f(x) = #
Draw a (horizontal) line at y = # The intersection points are points where the graph is f(x) = # f(x) = –2 f(x) = 2

Example Find f(1) Find f(–0.5) Find f(x) = 0 Find f(x) = –5

Your Turn: Complete Parts A – D for problems 7 – 14 on The Key Features of Function Graphs – Part III handout.