Subtracting Fractions 1

harpazo

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TheJason

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\(\displaystyle \dfrac{4x}{2} - \dfrac{5x}{y}\)

\(\displaystyle \dfrac{(4x)(y) - (2)(5x)}{(2)(y)} = \dfrac{(4x)(y)}{(2)(y)} - \dfrac{(2)(5x)}{(2)(y)}\)

Cancel out stuff.

\(\displaystyle \dfrac{4x}{2} - \dfrac{5x}{y} = \dfrac{2x}{1} - \dfrac{5x}{y}\)
 

TheJason

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So @MarkFL is this one and similar ones correct?
 

MarkFL

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What you want to do is combine terms...
 
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TheJason

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What answer would you get in that case? Is it the same one?
 

MarkFL

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I would reduce the first term as you did and then combine:

\(\displaystyle \frac{4x}{2}-\frac{5x}{y}=\frac{2x}{1}-\frac{5x}{y}=\frac{2xy-5x}{y}=\frac{x}{y}(2y-5)\)
 
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harpazo

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I would reduce the first term as you did and then combine:

\(\displaystyle \frac{4x}{2}-\frac{5x}{y}=\frac{2x}{1}-\frac{5x}{y}=\frac{2xy-5x}{y}=\frac{x}{y}(2y-5)\)
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MarkFL

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What you've ended up with is not equivalent to that with which you began. You multiplied the expression by \(2y\) which changes it.
 
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harpazo

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What you've ended up with is not equivalent to that with which you began. You multiplied the expression by \(2y\) which changes it.
Thanks. I will try again.