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�� 80. �� :�) (5x-5y)/x�(2x^2)/(y-x); �) (a^2-c^2)/c^2 :(c-a)/c; �) a/(ab-b^2 ) :a^2/(b^2-a^2 ); �) (x-y)^2/y^2 �y^2/(y^2-x^2 ); �) ...

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80. �� :

�) (5x-5y)/x�(2x^2)/(y-x);

�) (a^2-c^2)/c^2 :(c-a)/c;

�) a/(ab-b^2 ) :a^2/(b^2-a^2 );

�) (x-y)^2/y^2 �y^2/(y^2-x^2 );

�) (2a^2)/(25-5a) :10a/(a-5)^2 ;

�) m/(3m-3n)�(n^2-m^2)/m^2 .

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