\[\boxed{\text{708\ (708).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ 12b² - 12c^{2} =\]
\[= 12 \cdot \left( b^{2} - c^{2} \right) =\]
\[= 12 \cdot (b - c)(b + c)\]
\[2)\ 2a²c - 2b^{2}c =\]
\[= 2c\left( a^{2} - b^{2} \right) =\]
\[= 2c(a - b)(a + b)\]
\[3)\ 5a² - 20 = 5 \cdot \left( a^{2} - 4 \right) =\]
\[= 5 \cdot (a - 2)(a + 2)\]
\[4)\ 3mn² - 48m =\]
\[= 3m\left( n^{2} - 16 \right) =\]
\[= 3m(n - 4)(n + 4)\]
\[5)\ 7y³ - 7y = 7y\left( y^{2} - 1 \right) =\]
\[= 7y(y - 1)(y + 1)\]
\[6)\ a³ - a^{5} = a^{3}\left( 1 - a^{2} \right) =\]
\[= a³(1 - a)(1 + a)\ \]