Question 526669
{{{ x/(x+7) + x/(x-7) = (x*(x-7) + (x+7)*x) / ( (x+7)(x-7) ) }}}
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{{{ (x*(x-7) + (x+7)*x) / ( (x+7)(x-7) ) = (x^2 -7x + x^2 + 7x) /( (x+7)(x-7) ) }}}
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{{{ (x^2 -7x + x^2 + 7x) /( (x+7)(x-7) ) = (2x^2) / ( (x+7)(x-7) )}}}
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I'd say your book has a typographical error in it.
Look for a page or handout that is entitled "Errata".