Заполни пропуски

Упрости выражение:

1. \(\cfrac{6a^2-6b^2}{a^2+b^2}\ \cdotp \cfrac{7b^2+7a^2}{9b-9a}=\) [ ] \(=\) [ ];

2. \(\cfrac{a^3+8b^3}{a^2-4b^2}\ \cdotp \cfrac{2b-a}{4b^2-2ab+a^2}=\) [ ];

3. \(\cfrac{2x^3-72x}{4x} \vcentcolon (3x^2-36x+108)=\) [ ] \(=\) [ ];

4. \(\cfrac{m^2-1}{c^2-8c+16} \vcentcolon \cfrac{m^2+2m+1}{4-c} = \) [ ].