\[\boxed{\text{837.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ 7 \cdot (4a - 1)^{2} =\]
\[= 7 \cdot \left( 16a^{2} - 8a + 1 \right) =\]
\[= 112a² - 56a + 7\]
\[\textbf{б)} - 3 \cdot (5y - x)^{2} =\]
\[= - 3 \cdot \left( 25y^{2} - 10yx + x^{2} \right) =\]
\[= - 75y^{2} + 30xy - 3x²\]
\[\textbf{в)} - 10 \cdot \left( \frac{1}{2}b + 2 \right)^{2} =\]
\[= - 10 \cdot \left( \frac{1}{4}b^{2} + 2b + 4 \right) =\]
\[= - \frac{5}{2}b^{2} - 20b - 40\]
\[\textbf{г)}\ 3 \cdot (a - 1)^{2} + 8a =\]
\[= 3 \cdot \left( a^{2} - 2a + 1 \right) + 8a =\]
\[= 3a² - 6a + 3 + 8a =\]
\[= 3a² + 2a + 3\]
\[\textbf{д)}\ 9c² - 4 + 6 \cdot (c - 2)^{2} =\]
\[= 9c^{2} - 4 + 6 \cdot \left( c^{2} - 4c + 4 \right) =\]
\[= 9c² - 4 + 6c^{2} - 24c + 24 = 15c^{2} - 24c + 20\]
\[\textbf{е)}\ 10ab - 4 \cdot (2a - b)^{2} + 6b^{2} = 10ab - 4 \cdot \left( 4a^{2} - 4ab + b^{2} \right) + 6b^{2} =\]
\[= 10ab - 16a^{2} + 16ab - 4b^{2} + 6b^{2} = - 16a^{2} + 26ab + 2b²\ \]