Решите уравнение: а) 3x(x - 7) - x(4 + 3x) = 6

а) $3x(x - 7) - x(4 + 3x) = 6$ $3x^2 - 21x - 4x - 3x^2 = 6$ $-25x = 6$ $x = -0,24$ б) $x(4x + 1) - 7(x^2 - 2x) = 3x(8 - x) + 6$ $4x^2 + x - 7x^2 + 14x = 24x - 3x^2 + 6$ $-3x^2 + 15x = 24x - 3x^2 + 6$ $15x = 24x + 6$ $-9x = 6$ $x = -\frac{6}{9} = -\frac{2}{3}$ в) $\frac{x + 8}{3} - \frac{x - 2}{5} = 2$ Умножим на 15: $5(x + 8) - 3(x - 2) = 30$ $5x + 40 - 3x + 6 = 30$ $2x + 46 = 30$ $2x = -16$ $x = -8$ г) $\frac{9x - 5}{2} - \frac{5x + 3}{3} + \frac{1 - 4x}{4} = 5$ Умножим на 12: $6(9x - 5) - 4(5x + 3) + 3(1 - 4x) = 60$ $54x - 30 - 20x - 12 + 3 - 12x = 60$ $22x - 39 = 60$ $22x = 99$ $x = 4,5$ д) $14 - (2 + 3x - x^2) = x^2 + 4x - 9$ $14 - 2 - 3x + x^2 = x^2 + 4x - 9$ $12 - 3x = 4x - 9$ $21 = 7x$ $x = 3$ е) $\frac{7x - 3}{9} - \frac{4x + 3}{6} = x - 2$ Умножим на 18: $2(7x - 3) - 3(4x + 3) = 18(x - 2)$ $14x - 6 - 12x - 9 = 18x - 36$ $2x - 15 = 18x - 36$ $-16x = -21$ $x = 1,3125$