Решебник по алгебре 9 класс Мерзляк Задание 34

 

\[\boxed{\text{34\ (34).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]

\[1)\ 2a(5a - 7) - 5a(3 - 2a) =\]

\[= 10a^{2} - 14a - 15a + 10a^{2} =\]

\[= 20a^{2} - 29a\]

\[2)\ (2b - 3)(4b + 9) = 8b^{2} +\]

\[+ 18b - 12b - 27 =\]

\[= 8b^{2} + 6b - 27\]

\[3)\ (2c - 6)(8c + 5) -\]

\[- (5c + 2)(5c - 2) =\]

\[= 16c^{2} + 10c - 48c - 30 -\]

\[- 25c^{2} + 4 = - 9c^{2} - 38c - 26\]

\[4)\ 16m^{2} - (3 - 4m)(3 + 4m) =\]

\[= 16m^{2} - 9 + 16m^{2} = 32m^{2} - 9\]

\[5)\ (2x - 1)^{2} + (2x + 1)^{2} = 4x^{2} -\]

\[- 4x + 1 + 4x^{2} + 4x + 1 =\]

\[= 8x^{2} + 2\]

\[6)\ (x - 4)(x + 4) - (x - 8)^{2} =\]

\[= x^{2} - 16 - x^{2} + 16x - 64 =\]

\[= 16x - 80\ \]

\[\boxed{\mathbf{34.\ }Еуроки\ - \ ДЗ\ без\ мороки}\]

\[1)\ \frac{5}{6} \cdot ( - 2,57) + \frac{5}{6} \cdot ( - 3,43) =\]

\[= \frac{5}{6} \cdot ( - 2,57 - 3,43) =\]

\[= \frac{5}{6} \cdot ( - 6) = - 5\]

\[2) - 0,2 \cdot 4,8 - 4,7 \cdot ( - 0,2) =\]

\[= - 0,2(4,8 - 4,7) =\]

\[= - 0,2 \cdot 0,1 = - 0,02\]

\[3)\ 9 \cdot \left( 1 - \frac{1}{3} + \frac{1}{9} \right) =\]

\[= 9 \cdot 1 - 9 \cdot \frac{1}{3} + 9 \cdot \frac{1}{9} =\]

\[= 9 - 3 + 1 = 7\]

\[4)\ \left( - \frac{1}{19} + \frac{1}{38} \right) \cdot 38 =\]

\[= - \frac{1}{19} \cdot 38 + \frac{1}{38} \cdot 38 =\]

\[= - 2 + 1 = - 1\]