Question 94748
Multiply the following:
{{{(x/3 + 3/4)}}} * {{{(3x/4 - 3/5)}}}
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We need to put each pair of fractions over a single denominator, using a common
denominator much as you do in numerical fractions:
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Find the common denominator of the 1st pair: It would be 12, right?
{{{(x/3 + 3/4)}}} = {{{(4x + 3(3))/12}}} =  {{{(4x + 9)/12}}}
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Do the same with the 2nd pair of fractions, the common denominator would be 20:
{{{(3x/4 - 3/5)}}} = {{{(4(3x) - 4(3))/20)}}} = {{{(15x - 12)/20)}}}
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Now we have a single fraction times a single fraction
{{{(4x + 9)/12}}} * {{{(15x - 12)/20)}}}
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FOIL the numerators:
{{{(60x^2 -48x + 135x - 108)/240}}} = {{{(60x^2 + 87x - 108)/240}}}
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Factor out 3 in the numerator, then cancel it into the denominator:
{{{3(20x^2 + 29x - 36)/240}}} = {{{(20x^2 + 29x - 36)/80}}}; that's about all you can do with this
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