Решебник по математике 6 класс Ерина Виленкин рабочая тетрадь Часть 1, 2 Часть 2 | Страница 73

\[Стр.\ 73.\]

\[\boxed{\mathbf{3.}}\]

\[\textbf{б)}\ 7x - 8 + 5x = (7 + 5)x - 8 =\]

\[= 12x - 8\]

\[\textbf{в)}\ x - 5 + 3x = (1 + 3)x - 5 =\]

\[= 4x - 5\]

\[\textbf{г)} - 7x + 9 + 7x =\]

\[= ( - 7 + 7)x + 9 = 9\]

\[\textbf{д)}\ x + 2 - 4x = (1 - 4)x + 2 =\]

\[= - 3x + 2\]

\[\textbf{е)} - 8x - 7 + 8x =\]

\[= ( - 8 + 8)x - 7 = - 7\]

\[\boxed{\mathbf{4.}}\]

\[\textbf{б)}\ 7x - 5 - 4 \cdot (2x - 9) =\]

\[= 7x - 5 - 8x + 36 = - x + 31\]

\[\textbf{в)}\ 5 \cdot (x - 3) - (6x - 11) =\]

\[= 5x - 15 - 6x + 11 = - x - 4\]

\[\textbf{г)}\ x - 7 - 3 \cdot (2x - 8) =\]

\[= x - 7 - 6x + 24 = - 5x + 17\]

\[\textbf{д)}\ 6 \cdot (2x + 3) - 4 \cdot (7x - 20) =\]

\[= 12x + 18 - 28x + 80 =\]

\[= - 16x + 98\]

\[\boxed{\mathbf{5.}}\]

\[\textbf{б)}\ x = 2:\]

\[7x + 8 - 5 \cdot (3x + 2) =\]

\[= 7x + 8 - 15x - 10 =\]

\[= - 8x - 2 = - 8 \cdot 2 - 2 =\]

\[= - 16 - 2 = - 18.\]

\[\textbf{в)}\ x = - 3:\]

\[4 \cdot (5x - 1) - (7x - 8) =\]

\[= 20x - 4 - 7x + 8 =\]

\[= 13x + 4 = 13 \cdot ( - 3) + 4 =\]

\[= - 39 + 4 = - 35.\ \]

\[\textbf{г)}\ x = 4:\]

\[7 \cdot (2x - 1) + 4 \cdot (6x + 1) =\]

\[= - 14x + 7 + 24x + 4 =\]

\[= 10x + 11 = 10 \cdot 4 + 11 =\]

\[= 40 + 11 = 51.\]

\[\textbf{д)}\ x = 5\frac{3}{11}:\]

\[4 \cdot (3x + 3) - 3 \cdot (4x + 2) =\]

\[= 12x + 12 - 12x - 6 = 6.\]

\[\textbf{е)}\ x = - 9\frac{6}{7}:\]

\[- 9 \cdot (2x - 8) + 2 \cdot (9x - 10) =\]

\[= - 18x + 72 + 18x - 20 = 52.\]