Forget the name of it, but i need a review

  • Thread starter austin1250
  • Start date
  • #1
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Homework Statement



I basiclly just need a little review and maybe some 1 to show me how to solve out the equation/and equation like it. here is an example:

2x+1 / x-1 + 1/ x+1 = ?

Homework Equations


?



The Attempt at a Solution


?
 

Answers and Replies

  • #2
rock.freak667
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Homework Statement



I basiclly just need a little review and maybe some 1 to show me how to solve out the equation/and equation like it. here is an example:

2x+1 / x-1 + 1/ x+1 = ?


I assume by ? you mean a number like 3 or 2 or even some function f(x)?


but here's a clue

[tex]\frac{1}{a} + \frac{1}{b}= \frac{a+b}{ab}[/tex]
 
  • #3
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by Question mark i mean it would equal like 2x + 1 / x^2 - 1 or something along those lines
 
  • #4
rock.freak667
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by Question mark i mean it would equal like 2x + 1 / x^2 - 1 or something along those lines



then just bring them to the same common denominator (x-1)(x+1). Do you know how to do that?
 
  • #5
HallsofIvy
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I THINK you mean you want to add the two fractions (2x+1)/(x-1)+ 1/(x+1).
(Please use parentheses!)

As Rock.freak667 said, you need to get "common denominators". Here, the common denominator is (x-1)(x+1). Multiply numerator and denominator of the first fraction by x+1 and numerator and denominator of the second fraction by x-1.
 
  • #6
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then just bring them to the same common denominator (x-1)(x+1). Do you know how to do that?

no i forget, do you foil it ?
 
  • #7
29
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I THINK you mean you want to add the two fractions (2x+1)/(x-1)+ 1/(x+1).
(Please use parentheses!)

As Rock.freak667 said, you need to get "common denominators". Here, the common denominator is (x-1)(x+1). Multiply numerator and denominator of the first fraction by x+1 and numerator and denominator of the second fraction by x-1.

yeah, ok I did that and i got

(2x^2-x-1)/(x2-2x+1) + (x+1)/ (x^2 -2x-2)

now what
 
  • #8
rock.freak667
Homework Helper
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yeah, ok I did that and i got

(2x^2-x-1)/(x2-2x+1) + (x+1)/ (x^2 -2x-2)

now what

the denominator would be (x-1)(x+1)

now do as HallsofIvy said and

Multiply numerator and denominator of the first fraction by x+1 and numerator and denominator of the second fraction by x-1.
 
  • #9
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the denominator would be (x-1)(x+1)

now do as HallsofIvy said and

that just confused me. i did what halls said and i got the answer you quoted. so i did it wrong?
 
  • #10
rock.freak667
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that just confused me. i did what halls said and i got the answer you quoted. so i did it wrong?

[tex]\frac{2x+1}{x-1} + \frac{1}{x-1}[/tex]



[tex]= \frac{(2x+1)}{(x-1)(x+1)} + \frac{(x+1)}{(x-1)(x+1)}[/tex]

since the denominators are both the same, you can just add the numerators now.
 
  • #11
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[tex]\frac{2x+1}{x-1} + \frac{1}{x-1}[/tex]



[tex]= \frac{(2x+1)}{(x-1)(x+1)} + \frac{(x+1)}{(x-1)(x+1)}[/tex]

since the denominators are both the same, you can just add the numerators now.

did you copy that down wrong? its

(2x+1)/(x-1)+ 1/(x+1).
 
  • #12
rock.freak667
Homework Helper
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did you copy that down wrong? its

(2x+1)/(x-1)+ 1/(x+1).

Sorry there, forgot to do some more typing, should be this



[tex]
= \frac{(2x+1)(x+1)}{(x-1)(x+1)} + \frac{(x-1)}{(x-1)(x+1)}
[/tex]
 
  • #13
HallsofIvy
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Now, austin1250, use "FOIL" to multiply (x-1)(x+1) carefully! It is NOT [itex]x^2- 2x- 1[/itex].
 
  • #14
29
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Now, austin1250, use "FOIL" to multiply (x-1)(x+1) carefully! It is NOT [itex]x^2- 2x- 1[/itex].

oh did i say that? Sorry

x2-1
 

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