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Edited by DarkSpyda04:
7/23/2015 5:12:02 AM
18
I'm having trouble w/ an algebraic expression
I was having trouble simplifying an expression earlier but I just solved it now while I was posting this. However, I'm still a bit confused about the results. Here is the problem.
(x^n / x^n+1) / [x^2 * (x * x^-3)]
In the book, the solution is x^-1 but I kept getting x^-3
Here's how it's supposed to be done:
(x^n / x^n+1) / [x^2 * (x * x^-3)]
(x^n / x^n+1) / [(x^2 * x) * (x^2 * x^-3)]
(x^n / x^n+1) / [(x^2+1) * (x^2-3)]
(x^n / x^n+1) / [(x^3) * (x^-1)]
(x^n / x^n+1) / [x^3-1]
(x^n / x^n+1) / [x^2]
(x^n-n+1) / [x^2] (this is where I had trouble)
(x^1) / [x^2]
x^1-2
x^-1
I kept getting x^-3 because I used the calculator for (x^n / x^n+1) only to keep getting that it simplified to x^-1
Try 2^2 / 2^3 and you get the same result as x^-1
Try 3^4 / 3^5 and you get the same result as x^-1
If it truly were x^1 then the calculator would've returned the value for x that I gave it.
(x^-1) / [x^2]
x^-1-2
x^-3
I want to know why I kept getting that answer and why I was wrong.
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1 ReplyI agree with you, the answer is missing a parenthesis. x^n/x^(n+1) = x^(n-(n+1)) = x^(n-n-1) = x^-1
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2 RepliesEdited by Legoburn: 7/24/2015 1:28:50 AMI don't know what type of calculator you own, but maybe this helps. I substituted 2 for x and 5 for n. Also did it on paper because why not.
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I could easily help you, but it's hard for me to explain without talking to you. ^_^'
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Whenever I see something like (x^n / x^(n+1)), I just plug in two numbers, such as 3 and 4. The calculator is right, as dividing x^3 / x^4 results in 1/x. What you're messing up is the denominator of the complex fraction. x*x^-3 is just a fancy way of writing x^-2. When this is multiplied by x^2, you of course end up with x^0, or 1. The whole expression amounts to one of the twelve most basic functions: 1/x.
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6 Replies[quote] (x^n / x^n+1) / [x^2 * (x * x^-3)] (x^n / x^n+1) / [(x^2 * x) * (x^2 * x^-3)] (x^n / x^n+1) / [(x^2+1) * (x^2-3)] (x^n / x^n+1) / [(x^3) * (x^-1)] (x^n / x^n+1) / [x^3-1] (x^n / x^n+1) / [x^2] (x^n-n+1) / [x^2] (this is where I had trouble) (x^1) / [x^2] x^1-2 x^-1 [/quote] What is going on here? The very first step is wrong. The entire bottom simplifies to 1. I'm assuming the top is x^n/(x^(n+1)), which just simplifies to x^-1.
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Edited by SubjectBosco: 7/23/2015 11:42:14 PMOH SHIT, THIS IS AN ACTUAL ALGEBRA THREAD!
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3 RepliesEdited by EpicGameTime12: 7/24/2015 3:26:21 AMWhat the hell am I doing here? I mean, I'm good at math... [spoiler]But I haven't got to THIS shit yet![/spoiler] Edit: I should have clarified. I'm only 14 (heading to freshman this year), and not bad at math either (highest possible class).
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2 Replies((x^n )/ (x^(n+1))) Does this solve your problem? Your calculator might think x^n plus one instead of keeping the n+1 together.
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Sorry, can't help you.
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2 RepliesEdited by aceebro: 7/23/2015 10:26:27 AMStep two is wrong. Distribution doesn't work across multiplication, only addition. [spoiler]a(b+c)=ab+ac but a(b*c)=abc[/spoiler]I have no idea wtf textbook you're using that has that in there. EDIT: I realised that this likely isn't from a textbook, but my point stands. Wherever you saw that "how it's supposed to be done" is wrong, both with the distribution, and where they said that "x^(n-(n+1))=x^1". That doesn't even make any damn sense.
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1 ReplyEdited by Captain Korasi: 7/23/2015 6:27:16 AMToo.... many...... maths....
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Fųck I'm glad I don't have to do algebra ever. Teachers were wrong when they said it'd be useful in adulthood.
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What's the problem? When it's written x^n-n+1 it simplifies to x^1. How are you getting a -1?
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I'm assuming ^ means "to the power of"? I'll write this out and have a look.
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((x^n) /( x^n+1)) Try that.
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[spoiler]OP is FGT[/spoiler]
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4 RepliesFirst off, why are you solving an expression? Second off, what are you doing? What are you trying to do?
