Question 200904
a^-1b^-1  / a^2 -b^2  / ab
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please  check  to  assure  correct  problem.
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(a^-1 *b^-1)  / (a^2 -b^2)  /  (ab)
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as  with  fractions,   invert  and  multiply  instead  of  divide
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( a^-1 * b^-1)  * ( ab) / (a^2 -b^2)
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a^-1  =  1/a,,,,,,b^-1  =  1/b
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( 1/ab) * (ab) / ( a^2 -b^2)
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1/ ( a^2 - b^2 )