Homework Help Thread--SPLIT

[shapu]

Simple Math Question

What is -4^2? The BD Chat has been having a giant discussion about whether it is 16 or -16, so which is it?

Depends on how you frame it.

The poster above is absolutely correct.

It's 16. The reason people are getting -16 as a result is they're just putting -4^2 in a calculator. If you do (-4)^2, you'll get 16.

Let's break this down: To square a number is to multiply it by itself. Thus, -4^2 is the same as -4 x -4. The result is 16.

There is only one exception: i.

i^2 = -1.

So, sqrt(-1) = i, sqrt(-16) = 4i, and so on.

By the same token, you can remove i from negative roots.
sqrt(-9) = i*sqrt(9).

But, yeah. Back to the point of your question: -4^2 = 16 or -16, depending on whether there are parentheses. Strictly speaking, if you use the order of operations (PEMDAS), exponents come before the - sign (since that's the same as multiplying it by -1), so -4^2 = -(4*4) = -(16) = -16.

[fzun]

Calculus AB question!

We're learning how to find the volume of a solid generated by a graph around an axis of revolution using the disc/washer method and the shell method. I have a lot of trouble setting up the integral to solve these. Any tips? My teacher is really no help.

Also, since I'm having trouble remembering, can anyone explain how to do a Riemann sum? I need to know this for the AP exam and my textbook doesn't have any examples.

[Siniri]

Calculus AB question!

We're learning how to find the volume of a solid generated by a graph around an axis of revolution using the disc/washer method and the shell method. I have a lot of trouble setting up the integral to solve these. Any tips? My teacher is really no help.

Also, since I'm having trouble remembering, can anyone explain how to do a Riemann sum? I need to know this for the AP exam and my textbook doesn't have any examples.

Here's a pretty good explanation on Riemann sums. I vaguely remember the disc/washer method, but I'm not sure I can be of help without a specific example to work through -- it's been 11.5 years now since my last calculus class, and I've only used it for biostatistics and a few random puzzle-type things in the past 8 years. The same website has a description of the shell method -- actually, the washer method's on there, too, towards the bottom of that link. Maybe the alternate explanation will make more sense than your textbook's.

[Regan]

I'm working on a presentation to my social class about unethical practices of corporations. Does anyone know of a website that lists food/clothing/whatever companies that are owned by tobacco corporations? Are there any websites that list what major namebrand companies that are owned by unethical corporations? I have a bare list of some companies, but I'm having a hard time finding more information online (though that's probably because my searching skills seriously lack).

Thank you to anyone that can help.

[shapu]

Well, Nabisco was once part of RJR Nabisco, the RJR part being the Reynolds Tobacco Company. But it was spun off in like 1998.

Now that I think about it, I don't think there are too many companies that are owned by or sisters of tobacco companies that aren't ALSO tobacco companies.

EDIT: I would START with Wikipedia, and then find sources there to continue your search at your local library.

[Siniri]

Philip Morris became Altria a few years ago -- they used to own Kraft and some other major brands, but they spun those off. This site should give you some info about them (click the history link to find when they bought/sold other companies). We had to read the first 3 chapters of The Corporation for our business class -- it had some interesting arguments about corporate ethics -- it might give you some food for thought if you could find it at your library (or a local college library -- I was able to skim it in about half an hour).

Is your presentation on unethical practices or products? If it's practices, you don't have to limit yourself to tobacco companies -- try googling "corporate scandal" and you'll see what I mean. There was the whole accounting debacle (Enron, Worldcom) that brought about the Sarbanes-Oxley act, the subprime mess, lawsuits over marketing bad foods to kids (Kraft was in the thick of that one, as well as McDonald's), environmental impact issues, etc. Wal-mart's had a ton of issues, too -- discrimination, illegal workers, fair wage, predatory pricing...

If you want to stick to companies that sell vices but also other products under different brand names, try going directly to the corporate websites (of the parent company) -- under their "about" or "for investors" sections, they should have info about their brands. To find the parent company, the same areas should have the parent company name for any individual brand you look up. Shapu mentioned RJ Reynolds; they and Philip Morris are the 2 big tobacco companies left. Other vice industries include gambling (Harrah's is the only company I know of -- I'm not a gambler (or a smoker)). Gun companies might be owned by larger corporations, but I know even less about guns than gambling.

After the tobacco lawsuits, tobacco companies divested of their other businesses to protect them from the lawsuits (the US suits are mostly over, but they're still going on in other countries). Philip Morris actually has commercials here encouraging smokers to find out how to quit at their website. The smoking market is shrinking in the US but growing internationally, especially in developing countries. In the US, smokeless tobacco is growing, as are smoking cessation products (the ones containing nicotine are often manufactured by the tobacco companies).

I hope at least some of this info is useful.

[ginny-ROX]

hey i have to create a fictional story about anything and i need a idea of what to do it about
any ideas on what to do please post by monday(needed by friday but got to do 5 pages so kinda need ideas now)

thanks

[shapu]

Walk down the street. Find the first interesting person you see. The very first. No, "Well, not interesting enough," no "he's too ugly," or whatever.

See what he or she is doing.

Make up a story about why he or she is doing it, where they're coming from, where they're going to, what their home or office is like, what they do for a living, their blood sugar, whatever.

You'll do fine.

[ginny-ROX]

Walk down the street. Find the first interesting person you see. The very first. No, "Well, not interesting enough," no "he's too ugly," or whatever.

See what he or she is doing.

Make up a story about why he or she is doing it, where they're coming from, where they're going to, what their home or office is like, what they do for a living, their blood sugar, whatever.

You'll do fine.

Thank you for the thought but i think i will do something else
oh and just in case i want something totally unrelated to the real world

[shapu]

Make that person a secret ninja time traveller on a quest to assassinate the monkey pirate king.

[3lla]

Make that person a secret ninja time traveller on a quest to assassinate the monkey pirate king.

that ain't actually a bad story line....

[ginny-ROX]

Make that person a secret ninja time traveller on a quest to assassinate the monkey pirate king.

that ain't actually a bad story line....

no it's not but i have allready started because i got to do 10 pages.(sorry thought it was 5 but i wasn't listening properly)

[Tymaporer]

Whoo, necromancy! Okay, so normally I'm pretty good with Spanish grammar (even though the preterite tense needs to rot in hell). But these two sets have me stumped. For anyone who knows Spanish, can you help me identify the common (as in they all have the same) error in each of these sets of sentences? The first three sets had mistakes with infinitives, reflexives, and conjugations.

Set 4
Me pongo mi ropa.
Me cepillo mis dientes.
Me lavo mi pelo.
Educación es muy importante para tener un buen futuro.
Vengo a escuela en carro.
Me gusta comer cena con mi familia.

Set 5
Yo veo mis amigos durante el almuerzo.
No conozco Sr. Gorman, el nuevo consejero.

(I'll bet anything this will be ridiculously obvious in retrospect...)

[Plastic Ninja]

any thing you want to know about beastes i'll tell yay!if i dont know then ill look it up.

[Xaidread]

I got a big vocabulary test tomorrow (60 words) and need a way to test myself online (for free). There are two parts of the test; spelling+part of speech and "mastery" which is matching words with sentences.
I already got the list on what the words are, but some of the definitions have fallen out of my head and so did the parts of speech. I did have flash cards of the words, but I don't have all of them now.