Question 817031
Write as a rational expression: 
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1/x^2-1 + x/x^2-3x-4
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1/[(x-1)(x+1)] + x/[(x-4)(x+1)]
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lcd = (x-1)(x+1)(x-4)
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Write each fraction over the lcd::
[(x-4)/lcd] + [x(x-1)/lcd]
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Combine the numerators over the lcd::
= [x-4+x^2-x]/lcd
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Simplify::
= [x^2-4]/lcd
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Cheers,
Stan H.
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