Решебник по алгебре 7 класс Мерзляк ФГОС Задание 371

 

\[\boxed{\text{371\ (371).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[1)*\ \cdot (a - b + c) =\]

\[= - abc + b^{2}c - bc^{2}\]

\[*\ \cdot (a - b + c) =\]

\[= - bc \cdot a - bc \cdot ( - b) - bc \cdot c\]

\[*\ \cdot (a - b + c) =\]

\[= - bc \cdot (a - b + c)\]

\[*\ = \ - \text{bc.}\]

\[2)*\ \cdot \left( ab - b^{2} \right) = a^{3}b - a^{2}b^{2}\]

\[*\ \cdot \left( ab - b^{2} \right) = a^{2} \cdot ab - a^{2} \cdot b^{2}\]

\[*\ \cdot \left( ab - b^{2} \right) = a^{2} \cdot \left( ab - b^{2} \right)\]

\[*\ = a^{2}.\]

\[3) - 3a^{2} \cdot (* - *) = 6a^{3} + 15a^{4}\]

\[- 3a^{2} \cdot (* - *) =\]

\[= - 3a^{2} \cdot ( - 2a) - 3a^{2} \cdot \left( - 5a^{2} \right)\]

\[- 3a^{2} \cdot (* - *) =\]

\[= - 3a^{2} \cdot \left( - 2a - 5a^{2} \right)\]

\[(*\ - \ *) = \left( - 5a^{2} - 2a \right).\]

\[\boxed{\text{371.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[5x^{2}y^{4} = 6;\ \ \ \ \ \ x^{2}y^{4} = \frac{6}{5} = 1,2\]

\[1)\ 1,5x^{2}y^{4} = 1,2 \cdot 1,5 = 1,8\]

\[2)\ 25x^{4}y^{8} = \left( 5x^{2}y^{4} \right)^{2} = 6^{2} =\]

\[= 36\]

\[3) - 25x^{6}y^{12} = - 5^{2} \cdot \left( x^{2}y^{4} \right)^{3} =\]

\[= - 25 \cdot \left( \frac{6}{5} \right)^{3} = - 25 \cdot \frac{216}{125} =\]

\[= - \frac{216}{5} = - \frac{432}{10} = - 43,2\]