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1. \(\dfrac{a-b}{c+d} \vcentcolon \dfrac{b-a}{3c+3d}\) \(=\) \(\dfrac{a-b}{c+d} \cdot\) [ ] \(=\) [ ].
2. \(\dfrac{ab+3b^2}{ab^2+a^2b} \vcentcolon \dfrac{12b+4а}{4a^3b}\) \(=\) [ ] \(=\) [ ].
3. \(\dfrac{x^2-25y^2}{xy} \vcentcolon \dfrac{x^2-5xy}{2y}\) \(=\) [ ] \(=\) [ ].
4. \((4a^2-b^2) \vcentcolon \dfrac{6a-3b}{a+b}\) \(=\) \(\dfrac{4a^2 -b^2}{1} \cdot\) [ ] \(=\) [ ].
5. \(\dfrac{49m^3-mn^2}{5m} \vcentcolon (49m^2+14mn+n^2)\) \(=\) [ ] \(\vcentcolon \dfrac{49m^2+14mn+n^2}{1}\) \(=\) [ ].
6. \(\dfrac{b^3-b^2}{c^3+c} \vcentcolon \dfrac{b-b^2}{1+c^2}\) \(=\) [ ].