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MidnightVampire
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 Posted: Fri Jan 04, 2008 3:02 am Post subject: Algebra homework |
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Ok, well. I'm having trouble with these problems.
(5x-2)(-3xsquared+2x-10)
This is -3 x squared. I'm saying that because I don't know how to get the squared thing on the computer. I understand how to do this normally, but I don't know how to do this when its a 2 by a 3. |
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Stella Thomas
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| Posted: Fri Jan 04, 2008 6:03 pm Post subject: |
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(5x-2)(-3xsquared+2x-10)
=-15x^3+ 10x^2-50x-6x^2 -4x+ 20
^3 means to the power of three (or cubed), ^2 means squared. These are called indices, you probably know that. If two numbers are mulitplied by each other, the indices add. EG:
(x^2)(x^3) would equal x^5...
Can anyone help me, how do you finish off algebraic long division???? I've got the right numbers but the wrong signs... help, I'm having a nervous breakdown about it... |
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blacktiger3915
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| Posted: Fri Jan 04, 2008 6:13 pm Post subject: |
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| Hold on help is on the way. My brother is pretty good in Algebra. I'm better in Geometry. He's eating now. |
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TNCowgirl
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| Posted: Fri Jan 04, 2008 6:26 pm Post subject: |
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It is quite simple. I'll give you the way to lay it out but I wont give you the answer.
-3x^2+2x-10
5x^3-2
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Now what you are going to do is take the 5x^3 and multiple it by everything and then you will take and you will get something like this, I will be using fake numbers, so please do not think theses are right because they are not.
60^7-60^7+60
Now instead taking and putting the first answer you will get for multipling -2*-3x^2 under the 60^7 you will put it under the -60^7 like this:
-3x^2+2x-10
5x^3-2
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60x^7-60x^7+60
-60x^7 and so on, then you just finish it out
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60x^7-120x^7 and so on. not remember none of this is right but how you lay the format out. Alright, I hope that helps. |
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blacktiger3915
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| Posted: Fri Jan 04, 2008 6:30 pm Post subject: |
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| He left, but I got 7x-12-3xsquared. It's probably not right. |
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TNCowgirl
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| Posted: Fri Jan 04, 2008 7:29 pm Post subject: |
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| MidnightVampire, what do you need to do with the problem? Do you need to know how to factor it all out or are you solving for x? |
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Stella Thomas
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| Posted: Fri Jan 04, 2008 11:48 pm Post subject: |
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| TNcowgirl wrote: |
It isn't,  , Stella, what is your problem? |
Was that a "What's your problem dude? You're so bad at maths?" or a "Tell me your worries, I'm here to help."
My problem is algebraic long division. I don't have the problem with me at the moment, but if I'm dividing a number by x+1 and at the end I'm left with x-1, how do I get rid of it? I can't times it by one, and if I times it by minus one it gets all complicated. This is a (b) part in a question so it shouldn't be too hard, and I've always gotten long division up until now. And I was on the phone to my maths teacher sorting out all my other problems last night, I don't want to bother him again. |
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Saint Razorblade
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| Posted: Sat Jan 05, 2008 12:03 am Post subject: |
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Are you dividing polynomials in that, Stella?
If so, just use synthetic division, which I'll explain if that is indeed the case. ^^
-
P.S. www.purplemath.com is like, my saviour. |
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| Posted: Sat Jan 05, 2008 1:44 am Post subject: |
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When when multiplying two polynomials, you just have to get all of the elements of the one polynomial multiplied by all of the elements of the other polynomial. (That's how the FOIL method works for binomials.) In this case, the easiest way for me to do that is to split up the binomial and multiply each element by the trinomial. Thus:
5x(-3x^2+2x-10)-2(-3x^2+2x-10)
From there, just multiply it out and combine like terms. (Yeesh, I sound like my Algebra book... ) It sounds like you already know how to do that, so I'll let you finish it for yourself. But if you need more help, feel free to PM me.
Hope that helps!
P.S. Stella: You don't need to divide anything for this problem. You were doing fine the first time. (Except you forgot one of the negatives when you were multiplying. I made the same mistake the first time I tried it. ) You just needed to add all of the like terms and you would have been done. |
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Stella Thomas
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| Posted: Sat Jan 05, 2008 5:59 pm Post subject: |
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No, the division as for my own work... turns out I did it wrong...
What on earth are polynominals? I'm guessing you mean like, cubed, to the power of four, to the power of five etc. Then yes, yes I was. I just accidentally added instead of subtracted at one point and messed the entire problem up...
And now I'm hiding from the trigonometry that awaits... |
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logosgal
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| Posted: Wed Jan 09, 2008 4:49 am Post subject: |
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Ah. Okay. Polynomials are expressions that have several different terms added together. Like 5x-2 or -3x+2x-10. I can't remember the nice, neat textbook definition offhand, so I hope that makes sense.
Were you asking how to divide exponents, then? To divide exponents, you just subtract, so x^6 ÷ x^4 = x^2.
If you want to divide polynomials--like (-3x^2+2x-10) ÷ (5x-2)--then the easiest way for me is synthetic division, but I can't remember exactly how to do that right now.  I'd have to look at my algebra notes... |
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MidnightVampire
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| Posted: Wed Feb 13, 2008 4:46 am Post subject: |
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| Thanks! I sorta forgot that I posted this on here... oops. But now I fully understand it. Stella, I hope you understand now, but I can't help you (I'm not that good) |
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