\[\boxed{\text{829.}\text{\ }еуроки - ответы\ на\ пятёрку}\]
\[\textbf{а)}\ \left( a^{2} - 2b \right)^{2} = \left( a^{2} \right)^{2} -\]
\[- 2 \cdot 2a^{2}b + (2b)^{2} = a^{4} -\]
\[- 4a^{2}b + 4b²\]
\[\textbf{б)}\ \left( x^{3} + 3y^{4} \right)^{2} = \left( x^{3} \right)^{2} + 2 \cdot\]
\[\cdot 3x^{3}y^{4} + \left( 3y^{4} \right)^{2} = x^{6} +\]
\[+ 6x^{3}y^{4} + 9y^{8}\]
\[\textbf{в)}\ \left( 7a^{6} + 12a \right)^{2} = \left( 7a^{6} \right)^{2} + 2 \cdot\]
\[\cdot 7 \cdot 12a^{6}a + (12a)^{2} = 49a^{12} +\]
\[+ 168a^{7} + 144a²\]
\[\textbf{г)}\ \left( 15x - x^{3} \right)^{2} = (15x)^{2} - 2 \cdot\]
\[\cdot 15xx^{3} + \left( x^{3} \right)^{2} = 225x^{2} -\]
\[- 30x^{4} + x^{6}\ \]