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Mathematics 14 Online
OpenStudy (user123):

help

OpenStudy (user123):

\[\frac{ \frac{ 1 }{ x } -\frac{ 1 }{ 5 }}{ \frac{ 1 }{ x^2 } -\frac{ 1 }{ 25}}\]

OpenStudy (user123):

I got x/-x = -1

OpenStudy (user123):

|dw:1473956534552:dw| and what is

OpenStudy (user123):

25x^2

OpenStudy (mathstudent55):

There are 2 fractions in the numerator and 2 fractions in the denominator. The denominators of the 4 fractions are x, 5, x^2, and 25. What is the LCD of all 4 denominators?

OpenStudy (mathstudent55):

Great. Let's multiply the numerator and denominator of the main fraction by the LCD of all the small fractions to eliminate the small fractions.

OpenStudy (user123):

I got -1 as my fina result

OpenStudy (mathstudent55):

\(\Large = \dfrac{ 25x^2(\frac{ 1 }{ x } -\frac{ 1 }{ 5 })}{ 25x^2(\frac{ 1 }{ x^2 } -\frac{ 1 }{ 25})}\)

OpenStudy (mathstudent55):

\(\Large = \dfrac{ 25x - 5x^2}{25 - x^2}\) \(\Large = \dfrac{ 5x(\cancel{5 - x})}{(5 + x )(\cancel{5 - x})}\)

OpenStudy (mathstudent55):

\(\Large = \dfrac{ 5x}{5 + x}\)

OpenStudy (mathstudent55):

That's what I get

OpenStudy (user123):

I simplified the num and den seperatley, than divided the den by num.

OpenStudy (skullpatrol):

$$ x \ne \pm5$$ :-)

OpenStudy (mathstudent55):

Other approach: \(\Large \dfrac{ \frac{ 1 }{ x } -\frac{ 1 }{ 5 }}{ \frac{ 1 }{ x^2 } -\frac{ 1 }{ 25}}=\) \(\Large =\dfrac{ \frac{ 1 }{ x } -\frac{ 1 }{ 5 }}{ (\frac{ 1 }{ x } -\frac{ 1 }{ 5})( \frac{ 1 }{ x } +\frac{ 1 }{ 5} )}\) \(\Large =\dfrac{ \cancel{\frac{ 1 }{ x } -\frac{ 1 }{ 5 }}~~1}{ \cancel{(\frac{ 1 }{ x } -\frac{ 1 }{ 5})}( \frac{ 1 }{ x } +\frac{ 1 }{ 5} )}\) \(\Large =\dfrac{ 5x \times 1}{ 5x \times ( \frac{ 1 }{ x } +\frac{ 1 }{ 5} )}\) \(\Large =\dfrac{ 5x}{ 5 + x}\) ; \(x \ne \pm 5\)

OpenStudy (user123):

ehy do you have to put the 5x on the last step? Why not |dw:1473958432969:dw|

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