Sample Problems, Lesson 2.6
Sample Problems for this Lesson Course Home Page To the Notes Menu   Assignment  

2.6, #6. Given Problem.

2.6, #6. Given Problem.
Part(a)(i).
This is the definition that the book calls definition 1. It is just another form of the one below, called definition 2.
Use the definition of the function to write the problem in terms of the function. Note that in this problem, a = -1.
Factor the numerator as the difference of two cubes, and cancel the two like factors. Then substitute to find the limit.
Part (a)(ii)
This is definition 2 and the definition used by this website in the notes section.
Again, we follow the definition of the function.
We multiply out the cubes,
 

and simplify.

We cannot take this limit the way it is, so we try to simplify further. An h is factored out of the numerator.
The h's canel and we can now take the limit.
And finally, we can take the limit at the desired point when x = -1.
Part (b).

We use the slope-intercept form of a line. We already know the slope (3),  We also know the point (-1,-1). 
By substitution, we can find the y-intercept, b.

We now have the equation of the line tangent to the function at the point (-1,-1).
Part (c).

This is the first plot for the interval (-2,0)

This is the second plot for the interval (-1.2,-.8)
This is the thrid plot for the interval (-1.05,-.95)

2.6, #24, Given Problem.

2.6, #24, Given Problem.

locations / year
Part (a)(i).
To find average rate of change calculate the slope of the line containing the two points in question.

locations / year
Part (a)(ii).
Same process as above with two new points.

locations / year
Part (a)(iii).
Same process as above with two new points.

locations / year
Part (b).
We average the two previous answers to get an estimated instantaneous rate of change in 1996.
Scatterplot of given data points along with estimated tangent line to the point (1996,1015).

locations / year
My own estimate of two points that this estimated tangent line intersects: (1995,650), and (1997,1370). Find the slope.



 
Assignment
1-23, Odds
Lesson 2.6, Pages 148-150

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