Homework Help Thread

[Ulver]

My calculus teacher is excellent at teaching and knows the subject very well. He was an aerospace engineer I believe and ended up teaching at a high school because of economic issues.

Really I think you just need to put enough time into Calculus as necessary. Almost anyone can learn it and use it but some people will need to put in only a little effort and other people might need to put in a bit more effort.

 

[Firestorm]

Alright, so I need a help with a History Project. I've gotten all the info and pictures, but I still don't know how to make it look good. Like, for instance, I have to glue all the info and pictures on another sheet of paper, which is construction paper, but I don't know how to organize it. I got a B in this class last tri, mianly due to Projects and Presentations, and I'm hoping to end the year with an A.

Anybody?

Still confused as to what you're doing. Is this a research assignment? Are you presenting this? Does it have to be on construction paper? How large is this? I'm assuming it's a poster?

What grade are you in?

 

[Voltron]

Maybe it's just because I come from a good HS but I don't see why a HS teacher couldn't teach calculus. Basic calc concepts are very easy, it's just that the algebra you do with the problems that makes them hard. The conceptual parts of calculus like derivatives and integrals shouldn't give you any problems.

 

[sbc]

By the way, what is a modulus?

Unless there's anther modulus I don't know about, modulus is a form of division.

The quotient of modulus division is the remainder of integer division.

i.e. 79 mod 3 = 1, 20 mod 2 = 0, etc.
I've never used it outside of programming, and even then I haven't used it much.

Modulus in pure mathematics is basically the magnitude of a value or basically the positive value for a number and is denoted by |x|. For example |-1| is 1 and |2| is 2 etc.

It's important because you can't perform the ln function on negative numbers so when you come to introducing limits you wouldn't be able to do it with certain numbers unless you take the modulus, positive value, of it.

integral of sin x is -cos x - that is understood and remembered. Mainly because the derivatives are understood and remembered.

easy way to remember for me:

----->Differentiation
s    c
c    -s
<-----Integration

 

[striker64]

Anyone in here an Accounting major by chance? I'm having a lot of trouble with a consolidation concept. I'd ask my teacher if she didn't completely suck at teaching.

 

[chaos]

Modulus in pure mathematics is basically the magnitude of a value or basically the positive value for a number and is denoted by |x|. For example |-1| is 1 and |2| is 2 etc.

It's important because you can't perform the ln function on negative numbers so when you come to introducing limits you wouldn't be able to do it with certain numbers unless you take the modulus, positive value, of it.

Most people would refer to that as the absolute value. Taking the modulus is the remainder from integer division.

 

[ferron]

Danyul, the best advice i can give you is to stay calm. as long as you know the basics of algebra, trig and geometry, then you can get at the least a 550 by staying calm if you are a C student.
also, you should check up the schools you want to attend in the various college guides that exist. some only check score that relate to your intended major (since many expensive colleges ask what your major will be). that will help you know if you need to take it again or not.
....
as a side note, most colleges prefer a great GPA with a decent SAT score to a perfect SAT and decent GPA, since it shows more dedication.

 

[Phantom_IV]

Danyul, my advice is to double check your work. Make sure you arent forgetting any details, have the mental math straight, and are actually answering the question. Calmness is key, as well as just remembering the basics. Keep the concepts straight and other stuff should fall in line. And what the ivies care about is NOT a perfect SAT score. Anything above 2200 and below 2350 is weighted about the same. Decent scores (2100+ for asians, 2000+ if you're white, even lower if you're black/hispanic) are a prerequisite, but wont be a deciding factor in admission unless they also see you're struggling academically.
My best advice is to try to get important sounding positions in a variety of student associations, optimally with an elected position as well (NHS president, student body vice president, etc). MAKE SURE TO DO COMMUNITY SERVICE. LOTS OF IT. ESPECIALLY DURING THE SUMMER.
^^sorry about the caps, but this is an important point. It's rather easy to do and only requires some time. Don't volunteer at a library. Volunteer with some sort of program that helps poor/sick/elderly. Hospital volunteer is a great idea. If you happen to meet someone who dies, it makes a great essay topic too.
I know that sounds kinda heartless, but the whole process is kinda cutthroat. Chances are not good lol.

Well, good luck. I hope u end up doing better than me lol. I went 2340 sat, 800 math II, 800 physics, 780 us history, 10+ ap exams, captain of a bunch of academic teams, won first at the state level in all of them, etc. and still got screwed over. well, not completely. i'm doing biomed engineering at johns hopkins, but i woulda liked to have gotten into stanford.

 

[Polis4rule]

Danyul, the best advice i can give you is to stay calm. as long as you know the basics of algebra, trig and geometry, then you can get at the least a 550 by staying calm if you are a C student.
also, you should check up the schools you want to attend in the various college guides that exist. some only check score that relate to your intended major (since many expensive colleges ask what your major will be). that will help you know if you need to take it again or not.
....
as a side note, most colleges prefer a great GPA with a decent SAT score to a perfect SAT and decent GPA, since it shows more dedication.

They only care about that if you took difficult enough courses in high school. If you take 6-7 AP classes, or be in the IB program, obviously colleges will prefer you more than just a "high" GPA with other classes. Anything that is above like a 1900 on the SAT combined with a strength of class schedule and any of one's extra ciricular activities will add up to a decent looking person.

Of course, having higher SAT scores will look better and probably push one into the more elite schools, but anything is possible if one has a high enough GPA and extra ciriculars.

 

[Tytus]

If anyone needs any engineering mechanics help I could probably to be able to aid you, as well as physics and most stuff up to calc 3.

I often tutor my little sister in algebra as well so that's pretty fresh in my mind too.

 

[Onii]

Is anyone familiar with economics? I've got a few questions here:

1/ What is "moral hazard" all about? I wiki'd it and it mentioned something about "assymetric information", but what "information" are they talking about? How exactly does that cause one party to act to the detriment of the other?

2/ What is the distinction between a hold-out and a free-rider?

 

[y2zipper]

Is anyone familiar with economics? I've got a few questions here:

1/ What is "moral hazard" all about? I wiki'd it and it mentioned something about "assymetric information", but what "information" are they talking about? How exactly does that cause one party to act to the detriment of the other?

2/ What is the distinction between a hold-out and a free-rider?

I don't know the answer to number 2, but I did a little research on Moral Hazard. I wiki'd it also and I think I can explain it...

Moral Hazard basically refers to the idea that people will take more risks when they are not responsible for the consequences of that risk. Most of the examples I've seen are used in insurance.

For example, let's say I have insurance that protects my house in the event of robbery. This means that the insurance company has to pay all the damages if my house gets robbed. In other words, the insurance company is responsible for this risk. Because I have this insurance, I sometimes forget to lock my door when I go out.

If I did not have insurance, I would be responsible for the risk myself, and I would probably be a lot more cautious and never forget to lock my door. This is moral hazard because I act one way when I'm not responsible for the risk and another way when I am responsible for the same risk.

There are 2 parties here: me and the insurance company. When I don't lock my door (whether this is on purpose or I forget is irrelevant), my action is detrimental to the insurance company because it significantly increases the risk that my house will get robbed. This means the insurance company is at a greater risk of paying out.

The 2 party example can be used to explain information asymmetry. Information asymmetry simply means that one party has more information. It isn't specific information, but it is information regarding whatever situation is going on.

In the example I provided with me and the insurance company as the 2 parties, I would be the party with more information, simply because I know my intentions and thoughts and the insurance company does not. In this example, I behaved inappropriately from the perspective of the insurance company, because my neglect put the insurance company at greater risk.

I hope that helps.

 

[Black Buddha]

K I dunno if anyone reads this but what the heck:

I have a problem considering changing schools. Basically my dad has a transferable job and now we may have to move from london to cardiff at the end of academic year in UK perhaps. I have two problems with this:
Firstly, we are doing a coursework in geography on some city which is due in January 2009, and its like a 45 page thesis of sorts. And we're going to do most of it in class in Yr11, which I will miss. So I have no clue how Im gonna finish my thing.
Secondly, the GCSE options there have Geography, which I already do, but Art and D.T. I do Art right now, but I have done no DT before, no work using the tools and stuff, since I just recently moved into the UK from India, around 10 months ago.
Thirdly, its going to be quite a hassle trying to catch up around one years work before the GCSE Exams...
I've had to adjust to curriculum changes and stuff a lot of times, the last 3 yrs of school I have spent in 3 diff ones, but never had to do so at such a vital stage, a year before the board exams. And I REALLY CARE about my academics, due to the competitiveness today without gettng a good GCSE and then A Level( or AS whatever its called) there is little chance of getting into a good college and university, which will end up screwing my life cause I wanna do researchwork in particle physics or medicine, and since I wont get to do that I'll end up as a boring everyday employee for some boring old company leading a boring old life instead of potentially making a breakthrough :(
Please don't reply saying "Sucks to be you" and such, could someone really give a good answer?
And yes, I do look way too far into the future.

 

[sbc]

Is anyone familiar with economics? I've got a few questions here:

1/ What is "moral hazard" all about? I wiki'd it and it mentioned something about "assymetric information", but what "information" are they talking about? How exactly does that cause one party to act to the detriment of the other?

2/ What is the distinction between a hold-out and a free-rider?

tutor2u is a good economics website iirc

Asymetric information relates to the knowledge of buyers and sellers to the good they are buying. I think the main example is second hand cars, there is asymetric information as the owner knows the condition of the car whilst the buyer in theory does not. Theoretically this leads to market failure as the buyers do not know what is a "lemon" (crappy good) and what isn't hence are willing to pay a lower price for the good until the sellers are forced out of the market. Someone tell me if I'm right because I'm only 90% on this.

Free-rider is someone that takes advantage of the non-excludable property of a public good. Hope that helps.

 

[A2ZOMG]

Hmmm...

I'm going to throw out here that I'm going to major Biology, and that I aspire to be a high school Bio teacher.

Topics like these make me wish now that I wasn't a slacker at school lol...Seeing how many of the questions seem to be calculus related, and I got tired of math classes after precalculus honors. And classes I did well in like Biology 2 AP and Chemistry honors, I'm now wondering if I'm rusty in my knowledge about those. I'm taking Computer Science AP, but I'm still kinda a n00b at it so I probably am not that good at answering questions about that.

Now...if someone here understands something like...applying any old image to a Java Applet (like...one of my random JPEGs or GIFs on my computer), I'd appreciate a tip on that.

 

[Bologo]

Hey, sorry to bump this thread, but there's something I've been rather curious about.

Is there a name for the function -b^x? It's not an exponential function, since exponentials aren't allowed to have a base that's <0.

I tried looking around on google and such, but I haven't been able to find a name for this type of function. I'm just curious, because it has quite an interesting shape, with oscillations that keep getting bigger and bigger and bigger when b < -1.

Also, is it even possible for this function to have a derivative? Because I know that you can't take the ln of a negative number, but perhaps there's a different way to find this derivative that I don't know about.

 

[CarltheChemist]

Just going to make mention of the fact that I am a Chemistry major, and would be more than willing to help anyone with questions relating to chemistry, and to a lesser extent, math and physics (there are better people on these forums to ask about math/physics though). Feel free to drop me a PM if you have a homework question, or are just curious about some general aspect of chemistry.

 

[X-Act]

Hey, sorry to bump this thread, but there's something I've been rather curious about.

Is there a name for the function -b^x? It's not an exponential function, since exponentials aren't allowed to have a base that's <0.

I tried looking around on google and such, but I haven't been able to find a name for this type of function. I'm just curious, because it has quite an interesting shape, with oscillations that keep getting bigger and bigger and bigger when b < -1.

Also, is it even possible for this function to have a derivative? Because I know that you can't take the ln of a negative number, but perhaps there's a different way to find this derivative that I don't know about.

This is the first time I'm noticing this thread, so here goes my answer to this question.

First of all, I'm sure you mean (-b)^x and not -b^x. The graph of -b^x is, of course, the same as that of b^x but mirrored on the x-axis. I'm also assuming that the value of b is positive in your argument (so that -b is negative).

(-b)^x is different, though. For one thing, it is undefined in certain places. For example, if b>0, then (-b)^x is undefined when x = 0.5. It is actually undefined for all values of x that would result in an even root.

This function would not be continuous. One of the most important theorems in calculus is that differentiability always implies continuity. That means, by modus ponens, that if a function is not continuous at a certain point, then it is not differentiable at that point. So no, the function (-b)^x is not differentiable everywhere when b>0 (-b<0). In fact, I think (though I'm not 100% certain) that the function (-b)^x where b>0 is not differentiable almost everywhere, where the term 'almost everywhere' has an exact definition here.

As far as I know, this function has no famous recognisable name.

 

[Fuzznip]

I realize that I'm bumping this from a few months ago, but I could really use some help. Sorry if I can't do this.

Well, I'm in grade 10 science, and I'm currently in the chemistry unit. My teacher assigned a lab for us to do over the thanksgiving weekend, but I'm kind of lost as to what I need to do.

We had to do 9 separate lab experiments and record our observations and stuff like that in our chart, and we needed to explain the reactants, the type of reaction, etc. The chart is divided in these columns:

Reactants | Observations | Word Equation | Balanced Chemical Equation | Type of Reaction

Now, what I'm asking is about the latter 3 columns. I don't understand what I'm supposed to do for them. Well, I do know how to write a word equation and balance chemicals, but I don't know where I get the formulas and equations. By the way, the list of "Type of Reaction" is Formation, Decomposition, Single Replacement, Double Replacement, and Combustion. I just don't know which to pick... If someone can please help me with this, I will really appreciate it. Here's an example of a lab experiment I did:

Reactants: Copper (II) Chloride and Aluminum
Observations: Aluminum foil is breaking down and releasing gas.

So if someone can help me find the answer to that, then I will probably be able to do it with the rest of the experiments myself. Thanks!

 

[BlakBlastoise]

@ fuznip: if i understand your question, you want to know which kind of reaction use for your expiriment?
I would say to go for Double replacement. I would chose this because it is a pretty broad category. (most) Acid-Base reactions, as well as precipitaion reactions are also double replacement.

 

[Raj]

Okay, from what my teacher would have me do from along the same guidelines:
Observations- write every possible detail of your reactants before the experiment (color, texture, etc) and the result afterward

Word Equation- You're probably familiar with writing equations in the form: reactant + reactant ---> product. I believe your teacher wants you to specifiy in words what the reaction is (ie: this, when added to that yields X under this condition)

Chemical Equation: this would be when you're using the symbols to show the reactants--->product

Type of Reaction: no idea

If any of this seems familiar to you go for it!

 

[Fuzznip]

Thanks for the quick replies!

Okay, from what my teacher would have me do from along the same guidelines:
Observations- write every possible detail of your reactants before the experiment (color, texture, etc) and the result afterward

Word Equation- You're probably familiar with writing equations in the form: reactant + reactant ---> product. I believe your teacher wants you to specifiy in words what the reaction is (ie: this, when added to that yields X under this condition)

Chemical Equation: this would be when you're using the symbols to show the reactants--->product

Type of Reaction: no idea

If any of this seems familiar to you go for it!

Dragonites, that's basically what I have to do with my lab report. I know that the word equation is reactant + reactant = product, but how do I figure out the product? All I know is that the reactants are Copper (II) chloride and Aluminum, do you know how to figure out the product? I'm comfortable with the chemical equation to, but the same questions comes up again, what's the product?

As for the type of reaction, I really need to know what these are supposed to be (formation, decomposition, single replacement, double replacement, combustion).

If anyone needs the formulas for the type of reaction to get a better idea of what I need help with, I'll be happy to give them to you.

 

[BlakBlastoise]

Thanks for the quick replies!
If anyone needs the formulas for the type of reaction to get a better idea of what I need help with, I'll be happy to give them to you.

I think i might be able to help you. I know this type of chemisty but i'm having trouble with answering your question.

EDIT: i think i know what you mean now.
Reactants: Copper (II) Chloride and Aluminum
Observations: Aluminum foil is breaking down and releasing gas.

Co(Cl)2 + Al ---> ?
I think you're missing something here. I dont see how this could react since Al is -4 charge. You might be missign (O)2 as a reactant

 

[Fuzznip]

Co(Cl)2 + Al ---> ?
I think you're missing something here. I dont see how this could react since Al is -4 charge. You might be missign (O)2 as a reactant

Aluminum has a +3 charge, Copper has a +2 charge, and Chlorine has a -1 charge, if any of this means anything to you.

I tried answering this question myself, and this is what I came up with:

Word equation: Copper (II) chloride reacts with Aluminum.
Balanced Chemical Equation: CuCl2 + Al ==> AlCl3 + Cu
Type of Reaction: Single Replacement.

I am 0% sure if this is right...

 

[BlakBlastoise]

Aluminum has a +3 charge, Copper has a +2 charge, and Chlorine has a -1 charge, if any of this means anything to you.

I tried answering this question myself, and this is what I came up with:

Word equation: Copper (II) chloride reacts with Aluminum.
Balanced Chemical Equation: CuCl2 + Al ==> AlCl3 + Cu
Type of Reaction: Single Replacement.

I am 0% sure if this is right...

I get it now.
aluminum metal + copper(II) chloride --> aluminum chloride + copper metal

2 Al + 3 CuCl2 --> 2 AlCl3 + 3 Cu

I think. I keep making stupid type-o's so double check it.

Your equation was wrong since you had an extra Cl atom in the produdct. So it wasnt balanced.