\[\boxed{\text{820.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ (7 - 8b)^{2} = 7² - 2 \cdot 7 \cdot 8b +\]
\[= (8b)^{2} = 49 - 112b + 64b²\]
\[\textbf{б)}\ (0,6 + 2x)^{2} = 0,6² + 2 \cdot 0,6 \cdot\]
\[\cdot 2x + (2x)^{2} = 0,36 + 2,4x +\]
\[+ 4x²\]
\[\textbf{в)}\ \left( \frac{1}{3}x - 3y \right)^{2} = \left( \frac{1}{3}x \right)^{2} - 2 \cdot\]
\[\cdot \frac{1}{3} \cdot 3xy + (3y)^{2} = \frac{1}{9}x^{2} -\]
\[- 2xy + 9y²\]
\[\textbf{г)}\ \left( 4a + \frac{1}{8}b \right)^{2} = (4a)^{2} + 2 \cdot 4 \cdot\]
\[\cdot \frac{1}{8}ab + \left( \frac{1}{8}b \right)^{2} = 16a^{2} +\]
\[+ ab + \frac{1}{64}b²\]
\[\textbf{д)}\ (0,1m + 5n)^{2} = (0,1m)^{2} +\]
\[+ 5 \cdot 0,1 \cdot 2mn + (5n)^{2} =\]
\[= 0,01m² + mn + 25n²\]
\[\textbf{е)}\ (12a - 0,3c)² = (12a)^{2} - 2 \cdot\]
\[\cdot 12 \cdot 0,3ac + (0,3c)^{2} =\]
\[= 144a^{2} - 7,2ac + 0,09c²\]