Precal Blog

Today we started off by presenting the claims, and then Mr. Bieniek introduced a new concept pertaining to exponential functions.

He gave us the problem: If function f is exponential, and f(5)=12, and f(10)=18, find f(20).

To solve this problem we need to find the equation for f(x), and since f(x) is an exponential function we know the equation will look like y=ab^x. We know that when x is 5, y is 12, and we also know that when x is 10, y is 18. So we plug those numbers in to the model equation for x and y. The two equations we end up getting are 18=ab^10, and 12=ab^5. If we divide these two equations we can find the value of a. after dividing them we get 18/12=b^10/b^5. The rules of exponents tell us that when we have a fraction with the same base number in the numerator and denomonater multiplied to the different exponents we can simplify by keeping the base number and subtracting the exponents. so b^10/b^5=b^5, and 18/12=1.5, so 1.5=b^5. Then to find b we take the fifth root of 1.5, which is about 1.08. so b=1.08, and f(x)=a(1.08)^x. Next we need to find a. In order to do this we plug b into one of our previous equations based on information given. Let’s take 18=ab^10. Plug in 1.08 for b and we get 18=a(1.08)^10. 1.08^10=2.25, so 18=2.25a, and a=8. So, the final equation is f(x)=8(2.25)^x.

Last step, plug in 20 for x to find f(20). 8(2.25)^20=40.5, so f(x)=40.5 and our problem is solved.

So today we continued working on exponential functions in that packet. We spent most of the class working on it and at the end were given claims, which are 4, 7, and 15. These problems can be tricky, an important thing to remember is that the functions aren’t linear so they’ll never have a constant slope.

I believe I am the scribe for Hour 5 today so here we go…  We began class today by having a much needed Q&A time with Mr. Bieniek about stuff we didn’t understand about exponential functions and all that jazz we’ve been learning about.  After about 5-10 minutes or so of that he gave us the rest of the class period to work on the packet of info/problems on exponential functions.  He also gave us claims as well, they are: 4, 7, and 15.  Don’t forget to do a yellow sheet for the packet as well!!  The technical title of the packet is “Chapter A Section 1″.  Have a great rest of the day!

Hey all, Taylor here

okay so on friday we worked some more out of our packets that we got.  Make sure you do a yellow sheet for the reading in the packet and call it chapter A (I think) Sorry that this is late and not real in depth but i accidently left my packet at school but dont worry… i am going to get it like right now and i will explain everything we did then!! Thanks and write back in a bit!!

Hi everyone – Lindsay here!  I’m pretty sure I’m supposed to be hour five’s scribe for today, but I had to stay home, so I was wondering if someone could trade days with me for the blog?  I know the schedule’s already screwed up, but if someone else could do the post for today, that would be awesome

Much Appreciated!!!

Hey everybody!  No school until Tuesday!  4 and 5 exams tuesday, 6 and 7 on wednesday, dismissal at 10:20 both days!

By the way, if anyone still has any questions about the portfolio, might I suggest posting them?  No time like the present!  I’m sure someone will blog you back!

Hey everyone!  Monica’s right: school’s closed, hours 4 and 5 exams moved to friday!  Make sure you check the school website sometime tomorrow about hours 6 and 7.  And for those of you who are still trying to wrap up your portfolio, this may be the luckiest day of your high school carreer!  Study up tomorrow  (wishfull thinking, I know!) and make sure your portfolio and journal are done!  See everyone on Friday

check for yourself here::: todaytmj4.com/L03F007.htm”>