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# College Algebra. I am lost.

Registered User regular
edited January 2007
Quick history:

I have taken remedial college math three times (twice failed, once passed) and normal college algebra once (once failed, in it now). Needless to say, I am bad at math. Here I am however in math again trying to pass it so I can finally graduate college. I have tried the schools tutor sessions, but those only leave me more confused. I try harder in this class than any other. My pages are blanketed with notes about Linear Models and Equations, but I have not the slightest as to what those notes mean. So I come here, for help and or advice.

What can I do to understand math? Would anyone be willing to help me? I don't mean do it for me, but actually show me how to work things out and what some of the basic rules are.

Any help would be amazing.

EDIT: Here is what I am working on now and I can't get passed the first problem and I only have y=mx+b written down on number two.
http://math.acu.edu/math120/unit1/103linear.pdf

From what I understand, this is supposed to be very simple stuff.

projectmayhem on

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Registered User regular
edited January 2007
I could probably help you with the majority of this math, I am going for a math minor.

The easiest way of doing math like this, is what I was told in my physics class. Write down everything you know about your problem.

Problem 1 as an example. Im using spoilers incase you want to actually do this as you go.

Using the linear equation Y = mX + b you know it starts off as 20,000. That tells you on the equation, when x = 0, y = 20,000.
[spoiler:37cbbe6750]So 20,000 = m * 0 + b -> 20,000 = 0 + b -> 20,000 = b.
[/spoiler:37cbbe6750]

Now you want to find out what the slope is, in order to answer the question. So write out what else is given in the problem

When x = 10, y = 2,000. So plug that into what you know.
[spoiler:37cbbe6750]2000 = m * 10 + 20,000 -> 2000 - 20,000 = m * 10 -> -18000 = m * 10 -> -18000/ 10 = m -> -1800 = m

Now since you know m, you can write the full equation, y = -1800x + 20,000.[/spoiler:37cbbe6750]

Deswa on
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Registered User regular
edited January 2007
For future trouble check out www.purplemath.com It's a pretty good algebra resource.

jhunter46 on
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Registered User regular
edited January 2007
Well teaching math might be a bit much for a help thread. But maybe a few hints are in order.

It is a very famous axiom of Geometry that two points define a unique line. Correspondingly, in Algebra there is a formula to get a line from a pair of points. After glancing over your assignmnent, many of the problems (including the first) can be done by applying said formula. See if you can find that formula in your text book and the post it.

Depreciation. Office equipment was purchased for
$20,000 and is assumed to have a scrap value of$2,000
after 10 years. If its value is depreciated linearly, find
the linear equation that relates the value (V) in dollars
to time (t) in years.

You have 2 points of data above.
1: (t=0,V=20000)
2: (t=10,V=2000)

So plug those points into the formula you found and you should be good to go.

Some of the problems that don't fit into that pattern are simply "plug and chug" You are given a formula in "word problem" format and asked to apply it in a strait forward maner. The tricky part is being able to read word problems to get the formula right.

lowlylowlycook on

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Columbia, SCRegistered User regular
edited January 2007
I was writing a lengthy exposition on the topic, but since I've been repeatedly beaten to the punch I'll just give you the equation for finding the slope instead. It is:

m = (y2 - y1) / (x2 - x1)

In the first problem, V is dependent on t, so V goes in place of y and t in place of x. Then just use the points as provided by lowlylowlycook.

FunkyWaltDogg on
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Registered User regular
edited January 2007
Thanks so much for the help guys. I am sure more questions will arise as I go through, but it really means a lot that you guys are willing to help.

projectmayhem on
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Registered User regular
edited January 2007
I can relate man. Math has always been the hardest class I ever taken, and college math was the first class I ever flunked in my life.
I just found the actual textbook to be more really useful. I highlighted that book more than some of my Pols. Science books. Making notecards with formulas and examples, and going over them really helped too.

Kyougu on
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Blackwater Park, IARegistered User regular
edited January 2007
Slightly related, I guess: Can anyone recommend some good sites for information on more advanced stuff, Calculus and DiffEq and that? I've used Wikipedia a few times, but it's written by people with doctorates and I can't make heads or tails.

Kreutz on
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Hippo Hooray Registered User regular
edited January 2007
@Kreutz: http://www.howstuffworks.com/ :?:

I'm currently failing my maths as well, mostly because I didn't have the time to invest in it, anyway...

In the past I've had a private teacher for an hour or two per week (costly, but worth it, if it's really important to not being stuck without a degree), I would write down all problems I ran into that week and we would go over them together. I appeared I had a clear mind and was able to think logically, I just utterly failed at picking the right method to solve anything, he helped me getting a clear picture of what methods there exactly were to pick from in what cases. It helped me greatly.

(too bad I forgot half of that over the Summer holidays and now I'm stuck with chiÂ² crap and a test in 20 hours I am going to screw up so hard. :P)

Aldo on
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Registered User regular
edited January 2007
I have trouble with solving equations as well. For example I can't seem to grasp things like:

a = b(c/d) is the same as b = a(d/c)

It's like Goddamn magic.

My teacher told me it turns into second nature after practice, but I still forget simple things like that. I guess all I can say is practice, practice, practice and hope the test will be lenient. Having an answer sheet for the problems is certainly helpful, but still not very helpful if you can't make heads or tails of it.

Chen on
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Registered User regular
edited January 2007
Chen wrote:
I have trouble with solving equations as well. For example I can't seem to grasp things like:

a = b(c/d) is the same as b = a(d/c)

It's like Goddamn magic.

My teacher told me it turns into second nature after practice, but I still forget simple things like that. I guess all I can say is practice, practice, practice and hope the test will be lenient. Having an answer sheet for the problems is certainly helpful, but still not very helpful if you can't make heads or tails of it.

I teach math to high schoolers, and I always stress not to memorize stuff like that. Realize it's just an application of properties. Figure out WHY it works, don't just memorize it because you'll never use it that way...

a = (bc)/d, multiply both sides by d and you get:
ad = bc, divide both sides by c and you get:

Division and Mult properties of equality in practice.

musanman on
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Registered User regular
edited January 2007
Kreutz wrote:
Slightly related, I guess: Can anyone recommend some good sites for information on more advanced stuff, Calculus and DiffEq and that? I've used Wikipedia a few times, but it's written by people with doctorates and I can't make heads or tails.

If you're looking for an introduction to calculus, "Calculus" by Michael Spivak is the best you can get. It's theoretical, and it's tough, but it explains everything clearly and rigorously.

homeobocks on
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Registered User regular
edited January 2007
Chen wrote:
I have trouble with solving equations as well. For example I can't seem to grasp things like:

a = b(c/d) is the same as b = a(d/c)

It's like Goddamn magic.

It seems that way, but it's really just an application of the basic rule for any equation anywhere: Whatever you do to one side of the equation, do EXACTLY THE SAME THING to the other.

A common analogy is a 2-pan balance. The equation, at first, is balanced; each pan holds the same weight. If you change one (say, adding 1 pound), you have to do the same thing to the other. If you double the weight in one pan, you have to double the other side.

Of course, things get funky when you get to more complex equations, quadratics and trig and such.

GoodOmens on

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Do you have enemies then? Good. That means you’ve stood up for something, sometime in your life.Registered User regular
edited January 2007
musanman wrote:

I teach math to high schoolers, and I always stress not to memorize stuff like that. Realize it's just an application of properties. Figure out WHY it works, don't just memorize it because you'll never use it that way...

This man speaks the secret of Maths.

Tackle each new math theory like so.

Go through the theory, try and understand what the theory is on about and if possible why it is usefull. Try and figure out paterns and the like.

Slowly go through the worked examples your teacher of the book gave you. DRAW ALL OVER THEM in an attempt to figure out what happens in each steps. Write shortcut notes if you notice any.

Then tackle the problems in the work book trying to constantly reference back to the theory or the worked examples.

Remember maths is founded on basic principles always break it down and simplfy your problems. All your problems are exactly the same but with different layouts. Your job is to see how each layout can be broken down into the method to solve the problem.

Blake T on
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Registered User regular
edited January 2007
Seriously I don't memorize like...anything in math, that's why I love it

If I ever need a theorem (especially in my geometry classes) I can easily derive it. If they're too difficult to derive on the spot they're almost certainly fundamental in something else so it just becomes natural.

I got through my abstract algebra (note: abstract is nothing like algebra)using this, and I'll probably go for my master's in math in the fall.

Focus on concepts. If you ask why before you do anything in math you should get much further with less difficulty.

musanman on
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Registered User regular
edited January 2007
GoodOmens wrote:
Of course, things get funky when you get to more complex equations, quadratics and trig and such.

No, they don't. Not really. You have to remember that square roots can be negative or positive, and you have to remember that arcsin and arccos have limited domains (to cite your examples), but it's still the same concept (balancing sides of the equation).

homeobocks on
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Registered User regular
edited January 2007
musanman wrote:
I teach math to high schoolers, and I always stress not to memorize stuff like that. Realize it's just an application of properties. Figure out WHY it works, don't just memorize it because you'll never use it that way...

a = (bc)/d, multiply both sides by d and you get:
ad = bc, divide both sides by c and you get:

Division and Mult properties of equality in practice.
I understand this much. It gets a bit trickier (for me at least) when multiple fractions in a fraction, with (negative) exponents and the like, are in the equation.

You're absolutely right about understanding how it works, not memorizing how it works. I just envy people that see the solution in a glance without even using steps.

Chen on
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Registered User regular
edited January 2007
You have to realize that the core premise of any math subject is a thorough understanding of the basics. Any problem you see is a logical extension of more basic concepts you've learned earlier. If you try to skip something you're not familiar with early on and think you can just catch up later, you're screwed. Math is a subject in which memorization without understanding is absolutely useless - there will be problems on your final that you've never seen before, because you're expected to be able to figure out how it's done on the spot. This requires a certain type of thinking that just doesn't come naturally to some people.

If there's a problem that you just can't figure out at all, you're probably missing something from earlier. Scan through the chapter in the book and read the proofs of any concepts it introduces. Try to identify individual steps in there that you don't understand, and then look up the place in the book where that was proven. There are no shortcuts to learning math - you have to do it from the ground up, and make sure you have a solid foundation before moving on.

If you still just can't figure it out, ask your professor. It's worth swallowing your pride rather than paying to retake the subject over and over...

Zek on