document.write( "Question 315289: I've done this problem many times and gotten the wrong answer. Please help: (7)/(y^2-49)-(6)/(y^2-2y-35) \n" ); document.write( "

Algebra.Com's Answer #225578 by unlockmath(1688) $\"\"$ $\"About$

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Hello,
\n" ); document.write( "When subtracting fractions common denominators are needed.
\n" ); document.write( "In this (7)/(y^2-49)-(6)/(y^2-2y-35) we can factor the denominators to be:
\n" ); document.write( "(7)/[(y-7)(y+7)]-(6)/[(y-7)(y+5)]
\n" ); document.write( "So multiply the first fraction by (y+5)/(y+5) and the second fraction by (y+7)
\n" ); document.write( "to get:
\n" ); document.write( "7(y+5)/[(y-7)(y+7)(y+5)]-6(y+7)/[(y+5)(y-7)(y+7)]
\n" ); document.write( "Notice we now have the same denominators and this can be written as:
\n" ); document.write( "7(y+5)-6(y+7)/[(y+5)(y-7)(y+7)]
\n" ); document.write( "Expand the numerator out to get:
\n" ); document.write( "7y+35-6y-42/[(y+5)(y-7)(y+7)]
\n" ); document.write( "Combine like terms to get:
\n" ); document.write( "(y-7)/[(y+5)(y-7)(y+7)]
\n" ); document.write( "(y-7) cancels out to give us:
\n" ); document.write( "1/[(y+5)(y+7)]
\n" ); document.write( "Make sense?
\n" ); document.write( "RJ
\n" ); document.write( "www.math-unlock.com \n" ); document.write( "

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