October 01, 2006

Scribe Post:Day 16

Hi guys, this is Charlotte your first last scribe for cycle #1! I apologize for posted this blog so late because I had been busy working since Friday and my computer did not co-operate with me! Thanks to LInger for suggested to reset my computer, it works now.

Last Friday our class had a Pretest. It took us about half an hour or so to do it ourselves and then Mr. K. put us into groups of 3.
Around ten minute before class end, Mr. K told us the answer and went over the question’s #2 and the last question #6.


Heres the Question:

Question #2.)
How many zeroes does function f(x)=x2-e0.1x have?
A.) none B.) one C.) two D.) three E.) four

(Almost everyone answered letter C, because when we graph the function f(x) in Zoom Standard, it shows a parabola which crossed the x-axis twice.)




Answer: D.) three
Solution: By looking at the function f(x), we know that it’s a parabola because it has a highest exponent of 2, but since the x2 is subtracted by e0.1x, as x increases, the e0.1x would be greater than x2. Therefore there is a third zero.

To check if the third zero exist:
Option one:
1.) Graph the function f(x)=x2-e0.1x 2.) Hit 2nd table and hit down arrow. If you see the y-value decreases as the x-values increases, therefore there is a third zero.

Option two:
1.) Graph the function f(x)=x2-e0.1x
2.) Hit Zoom and hit
#0:Zoomfit

<<<<<>

(We know that if the third zero exist it would lay where x is positive. So we need to change our window in such a way that we can see the far right of the graph.)

3.) Hit WINDOW, then put 100 for Xmax. THen hit GRAPH



<<<< it would look like this


Question #6:
A sailing club is designing a new flag. The flag is to consist of a red triangle on a blue rectangular background. In the blue rectangle ABCD, DC measures 8 units and AD measures 6 units. E and F lie on AB and BC, x units form CB and C as shown in the figure.






a.) Show that the area, a, of the (shaded) triangle DEF, is given by a(x )=24-4x+1/2x2.

Solution: By looking at the diagram we know that:







1.) Now we can find the area of AFD, FBE , ECD and ABCD

The area of ABCD:






The area of AFD, FBE , ECD:

a.) we plug in 6 into h and 8-X into b
b.) we can reduce 6/2 = 3

c.) we then simplify the equation

-------------------------------------------

a.) we plug 6-X into h and X into b

b.) we then simplyfy the numerator

----------------------------------------------

a.) we plug 8 into h and X into b

b.) we can reduce 8/2=4


Now that we had all the areas, we can now find the area of the shaded triangle FED:









The a(x) does equal the area of the shaded triangle FED.

b.) What is the domain of the function a(x)? Solution: Since X is lesser than six, the domain is [0,6]

c.) Find the greatest and least possible values of the area of the triangle DEF. Solution: The greatest possible value is the Maximum of the graph, while the least greatest possible value is the Minimum of the graph.

Sorry for not giving you gys enough imformation about the answer in b and c , its because i cant think anymore my brain is all drain. I would appreciate it if any of you can explain it more! O yeah Before i forget...

Last friday on period 3, Mr. K showed us some website on the internet. He want us to sign up for http://flickr.com/. It's a social photo shared website. You can search a photo and used it aslong as it has a circle cc inside it. Its a Creative Comments Atribution, where we can use it aslong as it says it comes from them and we cant make money from it (non commercial). If the picture has a circle c, we have to ask permission by mailing the person from flickr. http://delicious.com/ is one of the site that we would need later on the course.

Yay, finally im done. I can't hardly open my eyes but before i pass out i would like to say that the NExt scribe would be>>>MaRk cRuZ<<<<>





2 comments:

linger said...

Hey Charlotte, nice graphs on your post! The only thing I have to suggest is fixing the font.. cause some of it is going over each other and I have no idea what it says, lol. But yeah, good job on your post ;)

Mr. H said...

With some simple formatting changes this excellent post would be worthy of the scribe post hall of fame.

Mr. Harbeck
Sargent Park School