Tuesday 25 February class

(after Test 1)

 

Topics: (some review from last time)

• Basic graphs: the graphs of the following functions are essential to know:

f(x) = |x| f(x) = x^2 f(x) = x^3

Important feature: this graph has an inflection point (the s-curve) at (0,0)

f(x) = \sqrt{x}

Important feature: the domain is only the interval [0, \infty)

f(x) = \frac{1}{x} (I forgot to mention this one today!)

Important feature: the graph approaches the lines x=0 and y=0 (the two coordinate axes). These lines are called asymptotes. Notice that x=0 is not in the domain.

• Transformations of graphs:

vertical translation (shift) – add a number to the output (value of the function)

horizontal translation (shift) – add a number to the input

reflection in the x-axis – multiply the output by -1

reflection in the y-axis – multiply the input by -1

[There are two transformations we did not discuss:

vertical stretching or squeezing – multiply the output by a positive number

horizontal stretching or squeezing – multiply the input by a positive number

We will return to these when we need them.]

• Even and odd functions:

Basically, even functions have graphs which have the same symmetry as the graph of y=x^2 and odd functions have graphs which have the same symmetry as the graph of y=x^3. The algebraic tests are tests for those symmetries.

 

Algebraic tests:

A function is even if and only if f(-x) = f(x) for all x in its domain.

A function is odd if and only if f(-x) = -f(x) for all x in its domain.

 

Homework:

• Reread/ review all the examples, making sure that you see how the transformations change the graphs (and why!) and how the algebraic test for an even or odd function checks the symmetry. You can use Piazza to discuss if you have questions.

• Do from Session 5: Exercise 5.1 (all), 5.2 (a-e), 5.5 (a-e)

• Make sure that you do the WeBWorK – there is an old one which is extended because there were some problems with it, and also a new, short one. They are due Tuesday (tomorrow!) by 11 PM, so start early!

• Make sure that you do the previously assigned Warm-Up (Warm-Up for Transformations) in Piazza, if you have not already done it. (You can only do it one time.) This is also extended to tomorrow 11 PM because of difficulties that came up in it, but there will be no more extensions!

 

* Please make sure that you have entered an email address in WeBWorK. I am still getting emails from WeBWorK that I cannot respond to because the students do not have email addresses in WeBWorK. Also, WeBWorK will be used to send out midterm grades later on.

 

* From now on you should expect that there will be a WeBWorK assignment and a Warm-Up every time (except when there is a Test in the next class meeting), and they will be due by 11 PM the evening before the next class meeting. You should always start early in case there are any difficulties. If you want to discuss how to solve the problems (or homework in general), please use Piazza!

 

* There is a Piazza app available so you can easily use the Piazza discussion board on your smart phone or iPod touch. See this page for more information.

• Make sure that you do the WeBWorK – there are two old ones which are extended because there were some problems with their dates. They are due Thursday ( day after tomorrow!) by 11 PM, so start early!

• Make sure that you do the previously assigned Warm-Up (Warm-Up for Transformations) in Piazza, if you have not already done it. (You can only do it one time.) This is also extended to tomorrow 11 PM because of difficulties that came up in it, but there will be no more extensions!

 

* Please make sure that you have entered an email address in WeBWorK. I am still getting emails from WeBWorK that I cannot respond to because the students do not have email addresses in WeBWorK. Also, WeBWorK will be used to send out midterm grades later on.

 

* From now on you should expect that there will be a WeBWorK assignment and a Warm-Up every time (except when there is a Test in the next class meeting), and they will be due by 11 PM the evening before the next class meeting. You should always start early in case there are any difficulties. If you want to discuss how to solve the problems (or homework in general), please use Piazza!

 

* There is a Piazza app available so you can easily use the Piazza discussion board on your smart phone or iPod touch. See this page for more information.

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