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H Precalclulus Ch. 12

4/29/2011

 
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Mrs. Johnson's 2015-2016 BC Calculus Students ROCK!
Second Period link
4/29/2011 02:07:46 am

Salutations from our math class

Ariel Epouhe
5/1/2011 07:22:32 am

Does anyone know how to graph sequences on the calculator?

Chandan Yashraj
5/1/2011 12:15:18 pm

What does the "n-1" mean on numbers 53 and 54 of section 12.1. Those are the only 2 problems on that page that have that, and I don't know why it's throwing me off. If someone could explain that would be nice.

@Ariel

It explains it well in the textbook in section 12.1. It's the last example where it has the 3 screen pictures.

Chandan Yashraj
5/8/2011 02:21:51 am

How would you solve numbers like 11-18 in section 12.2? The homework problems are 14 and 18. I am confused as to how they are deriving the equation.

Chandan Yashraj
5/8/2011 03:11:57 am

How would you solve number 37 and 39 in 12.2? The formula for solving "Sn" isn't working for this...

Kayla Simon
5/8/2011 05:36:16 am

Chandan,
For 39, you need to find n so you plug all of the info you know into the a=a1+(n-1)d, getting 49=5+(n-1)4 as your equation. Solving for n gets 12. From there, plug into the sum equation (S=n/2(a+an). With the numbers it is 12/2(5+49), and your final answer is then 324.

Kayla Simon
5/8/2011 05:43:15 am

I have no idea how to do problems 47 or 54 on the homework. Can anyone explain which equations they used and how?

Shivani D
5/8/2011 11:38:25 am

Hi Guys!
I wasn't here on Thursday or Friday, could anyone tell me what I missed? And our quiz is Tuesday not Monday right?

Chandan Yashraj
5/8/2011 01:25:09 pm

On Thursday we went over more of the summation problems and explored different types of those, and Friday we talked about using fraction decomposition and using it with sequencing problems to find the summation (we did the first problem of the worksheet that's up on the precalc tab, so I would suggest printing that off and using it to your advantage...it WILL be on Friday's test!!).

Yes, the quiz is rescheduled to Tuesday. But test is still Friday. :)

Chandan Yashraj
5/9/2011 11:52:27 am

On the telescoping worksheet with the partial fraction decomposition stuff, how do you know that the limit of the very last problem is 3/2? I was confused on this because the "cancelling out" for this problem is different from the other problems. Any help would be appreciated!

Alex Tazic
5/9/2011 12:04:55 pm

how do you know in the geometric equations if you should use n or n-1

Muhammed Alikhan
5/9/2011 12:11:49 pm

@Alex

for both types of sequences, you use the n and n-1 for the recursive form of the equation, where finding one term depends on the previous one. but for the explicit form where it doesnt depend on previous terms, you only use n.

Muhammed Alikhan
5/9/2011 12:29:54 pm

@Chandan

ok so once you decompose this, you get (1/n-2)-(1/n). What i find helpful is plugging in the first few numbers in the series, such as 1, 2 and 3 ,adding them up and see where that gets you close to. everything after that just gets smaller and smaller so its insignificant. in this case, its near 3/2.

Muhammed Alikhan
5/9/2011 12:30:02 pm

@Chandan

ok so once you decompose this, you get (1/n-2)-(1/n). What i find helpful is plugging in the first few numbers in the series, such as 1, 2 and 3 ,adding them up and see where that gets you close to. everything after that just gets smaller and smaller so its insignificant. in this case, its near 3/2.

Chandan Yashraj
5/9/2011 02:19:38 pm

@ Muhammed

Earlier I was trying the S1, S2, S3, etc. and solving for the partial sums to see to which value it came most closest to. For the other ones it was obvious as to what the value was, but for this one it was strange...why is it 3/2 and not something else?

Sorry if I sound stubborn with this problem, but I'm not understanding it.

Muhammed Alikhan
5/9/2011 02:49:56 pm

@Chandan

You know i don't think i understand it either because S1=-2 and it should be around there, and S2 doesn't even work given the decomposition, because you can't divide by 0. Sorry about that, but i dont think something like this will be on the quiz/test.

Chandan Yashraj
5/10/2011 12:55:29 pm

What is the exact difference between an explicit and a recursive form of the sequence formula?

Chandan Yashraj
5/10/2011 12:56:05 pm

besides the fact that recursive is n-1 and explicit is just n...?

Chandan Yashraj
5/10/2011 02:28:50 pm

For number 4 in section 12.4, why is it saying "if k(k+1)"? Shouldn't it be "if k(k+2)", hence what the problem says?

Alex Tazic
5/10/2011 11:33:26 pm

Recursive means your using the previous terms to get the next one while in explict you are not

Chandan Yashraj
5/11/2011 09:55:20 am

On the worksheets we did in class today, when it said to "prove" that the formula works for all real numbers, in the math induction worksheet...how do you prove it? I was completely stuck on this part. Thanks.

Vish Patel
5/15/2011 06:08:23 am

Chandan on the worksheets "proving" really means to just use S1, Sk, and Sk+1 to find the right side of the equation. Thats all you have to do. It was confusing to our class too but mrs. johnson explained that all you have to do is prove s for those three numbers

Shivani D.
5/15/2011 06:18:28 am

Hi guys! I had a quick question, how do your prove 19, on 12.4?

Chandan Yashraj
5/15/2011 02:06:45 pm

@ Vish

I know that Mrs. Johnson said to do just that, but looking at the book and what it's doing, isn't that ACTUALLY proving it? I'm just commenting on that, but if Mrs. johnson just wants us to do it that way then that's good enough I guess. Thanks anyway!

@Shivani

Just as Vish just said, you don't have to prove anything...just to S1, Sk, and Sk+1.


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