\[ c^2 - 16c = c(c - 16) \]
\[ 3a^2 - 6ab + 3b^2 = 3(a^2 - 2ab + b^2) \]
\[ a^2 - 2ab + b^2 = (a-b)^2 \]
\[ 3(a^2 - 2ab + b^2) = 3(a-b)^2 \]
Ответ: 2а) c(c-16); 2б) 3(a-b)²