Tuesday, April 15, 2008

Logarithmic Spiral

Today's class started of with a discussion on a picture that Mr. K had picked. The Picture was a snail shell. You ask what does a snail shell have to do with logarithms? well here is the answer. The answer is that a snail shell grows the same way a logarithmic spiral grows. But did you also know that a Tornado, Romanesc broccoli and even spiral galaxies. If you would like to learn more about logarithmic spirals here is a Wikipedia link.: http://en.wikipedia.org/wiki/Logarithmic_spiral


We then began to do a quiz. The answer and the questions were both published on this were blog. Some people did really good on the quiz some people didn't do so well.

After the quiz we then got into groups and began to have a race on which group could solve the most problems and get them correct ( A WORKSHOP CLASS).

the First question 3 ^ x = 12 was a question that we did last class, SO we got that answer very quickly. The next question 3 ^ (x+1) = 17 . This question has two ways that you can solve it one is in red and one is in green they are both right just to let you know.

The next question was 2(3) ^ x = 5. The first step would probably be to divide both sides by 2 and then turn the value's in to logarithms. Also keep in mind that you should write your logarithms correct or else you could possible lose marks. Okay back to the question is to isolate the x so that you can solve the question. The next part you just plug the values into your calculator.

The next question is log base 3 to the power of 5. AS you can see on slide 10 you rearrange the question until you get xlog3 ^ x = log 5 and from then on you solve for x and use your calculator.
The next question is basically the same concept.

The next question on slide 11 was a bit difficult and trick but here is how you do it. you rearrange the question using the power law. You then rearrange the question to make it solve for zero. after you have that done you then try and isolate the x. Once you have done that step you then see that x is equal to zero.

on slide 12 we did a similar question that we did from the previous slides before it. We then ran out of time and had to go to our next period classes.

Now on slide 13 i really did not know what happened but this is where we Started off again in the afternoon.

In the afternoon we started the beginning of class by writing an other short quiz. (can you believe it two quizzes in one day.) Anyways the answers and questions are both posted on the blog.

Now after that hard quiz we then got into our groups that you were in this morning. The first question that we did is found on slides 20 and 21. Where on slide 20 one classmate of mine decided to share his answer. When he was writing it onto the smart board he noticed that he had found and error. HE didn't decide to sit back down and quit he decided to share his error so he could let us learn from his mistake. What a Brave Person. the mistake that was made on slide 20 was that he thought that you could just place the 3 to the other side of the equal sign.
Anyways the right answer is on slide 21. As you can see the 3 is actually 5 to the power of 3 which is equal to 125. After that step you then rearrange the question to solve for zero. Now if you are wondering how to solve x you need to use the quadratic formula. If you forgot what it was here is an excellent way to never forget the quadratic formula.

x equals negative b
plus or minus the square root
of b squared minus 4ac
all over 2a
You will also need a catchy toon
..... how about pop goes the weasel.
All this information of this mnemonic http://pc30s.blogspot.com/2005/10/pop-goes-weasel.html

Okay back to the question, You then come up with two answers. if you are wondering why you reject the question this is the reason: An argument on a logarithmic equation can never be negative. if you get a negative argument you then have to reject the answer.

The next question on slide 22 was a question a lot of us never got to finish but Mr. K did this question was similar to the last one but you ask what is the anti log : well an anti log is the inverse of finding the log. You use it to get rid of the logs. You wont get marks off if you don't put it on but i think if you do put it you will be marks rewarded.

Well that was my scribe post i hope that it was useful. The next scribe will be Thi.

1 comment:

m@rk said...


Good scribe post. I learned a couple of things from your post. First, I didn't know that snail shells, tornado , spiral galaxies and even Romanesque broccoli grows the same way as the logarithmic spiral. Second, i need to do 2 quizzes tomorrow. Lastly, just a word of advice, you might want to highlight some parts of your scribe post if you are trying to emphasize an important concept.