Section 2.2 More on Functions and Their Graphs
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Transcript of Section 2.2 More on Functions and Their Graphs
Section 2.2 More on Functions and Their Graphs
Increasing and Decreasing Functions
The open intervals describing where functions increase, decrease, or are constant, use x-coordinates and not the y-coordinates.
Example Find where the graph is increasing? Where is it decreasing? Where is it constant?
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y
Example
Find where the graph is increasing? Where is it decreasing? Where is it constant?
x
y
Example
Find where the graph is increasing? Where is it decreasing? Where is it constant?
x
y
Relative Maxima And
Relative Minima
Example Where are the relative minimums? Where are the relative maximums?
Why are the maximums and minimums called relative or local?
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Even and Odd Functionsand Symmetry
A graph is symmetric with respect to they-axis if, for every point (x,y) on the graph,the point (-x,y) is also on the graph. All evenfunctions have graphs with this kind of symmetry.
A graph is symmetric with respect to the origin if, for every point (x,y) on the graph, the point (-x,-y) is also on the graph. Observe that the first- and third-quadrant portions of odd functions are reflections of one another with respect to the origin. Notice that f(x)and f(-x) have opposite signs, so that f(-x)=-f(x). All odd functions have graphs with origin symmetry.
Example
Is this an even or odd function?
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Example
Is this an even or odd function?
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Example
Is this an even or odd function?
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Piecewise Functions
A function that is defined by two or more equations overa specified domain is called a piecewise function. Many cellular phone plans can be represented with piecewise functions. See the piecewise function below:A cellular phone company offers the following plan: $20 per month buys 60 minutes Additional time costs $0.40 per minute.
C t 20 if 0 t 6020 0.40( 60) if t>60t
Example
Find and interpret each of the following.
C t 20 if 0 t 6020 0.40( 60) if t>60t
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60
90
C
C
C
ExampleGraph the following piecewise function.
f x 3 if - x 32 3 if x>3x
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Functions and Difference Quotients
See next slide.
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2
2 2
f(x+h)-f(x) for f(x)=x 2 5h
f(x+h)
f(x+h)=(x+h) 2(x+h)-5
x 2 2 2 5
Find x
First find
hx h x h
Continued on the next slide.
2
2 2 2
2 2 2
f(x+h)-f(x) for f(x)=x 2 5h
f(x+h) from the previous slidef(x+h)-f(x) find
h x 2 2 2 5 x 2 5f(x+h)-f(x)
h x 2 2 2 5 2 5
2
Find x
Use
Second
hx h x h x
hhx h x h x x
h
2 2
2 2
2x+h-2
hx h hh
h x hh
Example
Find and simplify the expressions iff(x+h)-f(x)Find f(x+h) Find , h 0
h
( ) 2 1f x x
Example
Find and simplify the expressions if f(x+h)-f(x)Find f(x+h) Find , h 0
h
2( ) 4f x x
Example
Find and simplify the expressions if f(x+h)-f(x)Find f(x+h) Find , h 0
h
2( ) 2 1f x x x
Some piecewise functions are called step functionsbecause their graphs form discontinuous steps. One suchfunction is called the greatest integer function, symbolizedby int(x) or [x], whereint(x)= the greatest integer that is less than or equal to x.For example,int(1)=1, int(1.3)=1, int(1.5)=1, int(1.9)=1int(2)=2, int(2.3)=2, int(2.5)=2, int(2.9)=2
Example
The USPS charges $ .42 for letters 1 oz. or less. For letters2 oz. or less they charge $ .59, and 3 oz. or less, they charge $ . 76. Graph this function and then find the following charges.a. The charge for a letter that weights 1.5 oz.b. The charge for a letter that weights 2.3 oz.
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$1.00$ .75$ .50$ .25
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(b)
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(d)
There is a relative minimum at x=?
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20
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(a)
(b)
(c)
(d)
2Find the difference quotient for f(x)=3x .
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3 666
x xhx hx
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(b)
(c)
(d)
Evaluate the following piecewise function at f(-1) 2x+1 if x<-1f(x)= -2 if -1 x 1 x-3 if x>1
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