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Mathematical Expression Editor
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We will give some general guidelines for sketching the plot of a function.
Let’s get to the point. Here we use all of the tools we know to sketch the graph of
:
Compute and .
Find the -intercept, this is the point . Place this point on your graph.
Find any vertical asymptotes, these are points where goes to infinity as
goes to (from the right, left, or both).
If possible, find the -intercepts, the points where . Place these points on
your graph.
Analyze end behavior: as , what happens to the graph of ? Does it have
horizontal asymptotes, increase or decrease without bound, or have some
other kind of behavior?
Find the critical points (the points where or is undefined).
Use either the first or second derivative test to identify local extrema
and/or find the intervals where your function is increasing/decreasing.
Find the candidates for inflection points, the points where or is undefined.
Identify inflection points and concavity.
Determine an interval that shows all relevant behavior.
At this point you should be able to sketch the plot of your function.
Sketch the plot of .
Try this on your own first, then either check with a friend, a graphing calculator (like
) or check the online version.
Compute and ,
The -intercept is . Place this point on your plot.
Which of the following are vertical asymptotes? Select all that apply.
In this case, , we can find the -intercepts. There are three intercepts. Call them , ,
and , and order them such that . Then
Which of the following best describes the end behavior of as ?
Which of the following best describes the end behavior of as ?
The critical points are where , thus we need to solve for . This equation has two
solutions. If we call them and , with , then what are and ?
Mark the critical points and on your plot.
Check the second derivative evaluated at the critical points. In this case, hence ,
corresponding to the point is a local
and , corresponding to the point is local
of . Moreover, this tells us that our function is
on ,
on , and
on . Identify this on your plot.
The candidates for the inflection points are where , thus we need to solve for
.
The solution to this is .
This is only a possible inflection point, since the concavity needs to change to make
it a true inflection point.
is concave
to the left of this point
is concave
to the right of this point
So this point
a point of inflection.
Since all of this behavior as described above occurs on the interval , we now have a
complete sketch of on this interval, see the figure below.
Sketch the plot of
Try this on your own first, then either check with a friend, a graphing calculator (like
), or check the online version.
Since this function is piecewise defined, we will analyze the cases and
separately.
The derivative of on is
The second derivative of on is
The derivative of on is
The second derivative of on is
Because is piecewise defined, and potentially discontinuous at , it is important to
understand the behavior of near .
Moreover,
Record this information on our graph with filled and unfilled circles.
Which of the following are vertical asymptotes on ? Select all that apply.
Which of the following are vertical asymptotes on ? Select all that apply.
Which of the following best describes the end behavior of as ?
Which of the following best describes the end behavior of as ?
We mark the location of the horizontal asymptote:
The critical points are where or does not exist. is a critical point, since we
have already seen it is a point of discontinuity for , and thus does not exist
there.
On , has a critical point at
On , has a critical point at
Mark the critical points and on your plot.
Using the first derivative, we can see that
On , is
.
On , is
.
On , is
.
On , is
.
The candidates for the inflection points are where .
On , has one zero, namely . The sign of changes from
through this point.
On , has one zero, namely . The sign of changes from
through this point.
Since all of this behavior as described above occurs on the interval , we now have a
complete sketch of on this interval, see the figure below.
Start typing the name of a mathematical function to automatically insert it.
(For example, "sqrt" for root, "mat" for matrix, or "defi" for definite integral.)
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Start typing the name of a mathematical function to automatically insert it.
(For example, "sqrt" for root, "mat" for matrix, or "defi" for definite integral.)