Precalculus 1/13/09

Student quote of the day " e is hiding....." Kush

Today we learned how to solve equations that involved logarithms. Here are a couple examples chosen by the 5th period students...

Example #1 An equation involving natural logarithms




subtract 4 from both sides

divide both sides by 3

write in exponential form "e is hiding"

solve for x

Example #2 equation involving multiple logarithms




use log property (log A+log B) = log(A*B)

write in exponential form " 2 is not hiding"

simplify

get equal to zero

factor

x=5 and x = -1 would seem to be the answers, but -1 does not work (it's called an extraneous solution) because it makes the argument(the (x-1) or x-3) spot in the original equation) negative. So the answer is x = 5

Helpful hint: Always get log or ln by itself before turning an equation into exponential form.

You can find other notes at Mr. Corn's web page here

Blog posting requirements

If it is your turn to post to the Madeira Precalculus blog, here is the rubric for your post. Each post is worth 10 points. Here's the breakdown:

1 point - Name and title

1 point - Date

2 points - time of post (before 6:00 pm)

5 points - include any definitions, important ideas, steps, equations, graphs and most importantly, any helpful hints that would help other students. Any good student quotes of the day would also be fun...

Use the sitmo gadget to enter equations and Geogebra to enter graphs. There are movie links on how to do this.

Always make a link to my web page at http://web.mac.com/jeffcorn/iweb

Have fun with this!

Precalculus 1/12/09

Student quote of the day..

"e ain't no friend of mine" - Kush

Today we learned how to solve exponential equations. The main strategy we use is to take the logarithm of both sides. Here's an example.



take the log of both sides

use a log property

solve for x


Here's another example involving the number e...



since the base is e, taking the natural log of both sides

use a log property

the ln e = 1

get x by itself using algebra


other examples can be found on Mr. Corn's web page here

Helpful hints...Can use calculator to check by getting decimal answer, storing a variable(use sto key), and substitute into original problem for x

Graph test

Here's a test of graphsketch.com. Ben's portfolio...

Girls ARE equal to boys in maths but lack confidence in ability, study shows

Interesting article from London...

Girls math article here

and yes, our quiz is still tomorrow...

Mathmaticious

Here's a video that's a play on Fergie's Fergalicious....This student was a freshman when he did this!




Mathmaticious Video

Blogging info...

Here's a short movie on how to set up your blog for Google accounts...

2010-01-04_1328