How to Simplify Complex Fractions Algebraically?

  • Thread starter Thread starter Gringo123
  • Start date Start date
  • Tags Tags
    Fraction
AI Thread Summary
To simplify the complex fractions x/(3x-1) - 2/(8x-1), first find a common denominator, which is the product of the two denominators since they have no common factors. Multiply the numerator of the first fraction by the denominator of the second and vice versa. This results in a single fraction with a combined numerator that can be simplified further. An example formula for this process is (A × D - C × B) / (B × D). This method effectively consolidates the fractions into a simpler form.
Gringo123
Messages
141
Reaction score
0
How do I tackle this problem?

Express the following as a single fraction in its simplest form:

x/3x + 1 - 2/8x-1
 
Physics news on Phys.org
I presume you mean
\frac{x}{3x-1} - \frac{2}{8x-1}

which would have been better written x/(3x-1)- 2/(8x-1).

To subtract fractions, get a common denominator. Here, since 3x-1 and 8x-1 have no common factors, just multiply numerator and denominator of the first fraction by 8x- 1 and of the second fraction by 3x-1.
 
HallsofIvy said:
I presume you mean
\frac{x}{3x-1} - \frac{2}{8x-1}

Slight typo, should be:

\frac{x}{3x+1} - \frac{2}{8x-1}

:wink:

But yes, so multiply top part of the first fraction by the denominator of the second fraction, and also top part of the second fraction by the bottom of the first fraction. Multiply the two denominators together. This will give you a single fraction and some terms on top which you can then deal with easily :smile:

Here's a simply little algebraic example to demonstrate the method:

\frac{A}{B}-\frac{C}{D}=\frac{(A \times D)-(C \times B)}{B\times D}

Hope that all helps now. :smile:
 
Last edited:
I tried to combine those 2 formulas but it didn't work. I tried using another case where there are 2 red balls and 2 blue balls only so when combining the formula I got ##\frac{(4-1)!}{2!2!}=\frac{3}{2}## which does not make sense. Is there any formula to calculate cyclic permutation of identical objects or I have to do it by listing all the possibilities? Thanks
Essentially I just have this problem that I'm stuck on, on a sheet about complex numbers: Show that, for ##|r|<1,## $$1+r\cos(x)+r^2\cos(2x)+r^3\cos(3x)...=\frac{1-r\cos(x)}{1-2r\cos(x)+r^2}$$ My first thought was to express it as a geometric series, where the real part of the sum of the series would be the series you see above: $$1+re^{ix}+r^2e^{2ix}+r^3e^{3ix}...$$ The sum of this series is just: $$\frac{(re^{ix})^n-1}{re^{ix} - 1}$$ I'm having some trouble trying to figure out what to...

Similar threads

Back
Top