\[\boxed{\text{852.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ 16a² + 56a + 49 = (4a + 7)²\]
\[*\ = 16a^{2}.\]
\[\textbf{б)}\ 36 - 12x + x^{2} = (6 - x)²\]
\[*\ = x^{2}.\]
\[\textbf{в)}\ 25a^{2} + 5ab + \frac{1}{4}b^{2} = \left( 5a + \frac{1}{2}b \right)^{2}\]
\[*\ = 5ab\]
\[\textbf{г)}\ 0,01b² + 2bc + 100c² = (0,1b + 10c)²\]
\[*\ = 2bc\]