3. Решите уравнение: 1) а) 3(1 - 2x) - 5(3 - x) - 6(3x - 4) = 83; б) 23 - 3(b + 1) + 5(6b - 7) - 7(3b - 1) = 0; в) x(2x + 3) - 5(x^2 - 3x) = 3x(7 - x); 2) а) 2m + m(3 - (m + 1)) = m(2 - m) + 12; б) 7 + 3(-k - 3(k + 5)) = 5(7 - 2k) + k.

### Решение уравнений **1) а) $3(1 - 2x) - 5(3 - x) - 6(3x - 4) = 83$** $3 - 6x - 15 + 5x - 18x + 24 = 83$ $-19x + 12 = 83$ $-19x = 71$ $x = -\frac{71}{19} \approx -3,737$ **1) б) $23 - 3(b + 1) + 5(6b - 7) - 7(3b - 1) = 0$** $23 - 3b - 3 + 30b - 35 - 21b + 7 = 0$ $6b - 8 = 0$ $6b = 8$ $b = \frac{8}{6} = \frac{4}{3} = 1\frac{1}{3}$ **1) в) $x(2x + 3) - 5(x^2 - 3x) = 3x(7 - x)$** $2x^2 + 3x - 5x^2 + 15x = 21x - 3x^2$ $-3x^2 + 18x = 21x - 3x^2$ $18x = 21x$ $3x = 0$ $x = 0$ **2) а) $2m + m(3 - (m + 1)) = m(2 - m) + 12$** $2m + m(3 - m - 1) = 2m - m^2 + 12$ $2m + m(2 - m) = 2m - m^2 + 12$ $2m + 2m - m^2 = 2m - m^2 + 12$ $4m - m^2 = 2m - m^2 + 12$ $2m = 12$ $m = 6$ **2) б) $7 + 3(-k - 3(k + 5)) = 5(7 - 2k) + k$** $7 + 3(-k - 3k - 15) = 35 - 10k + k$ $7 + 3(-4k - 15) = 35 - 9k$ $7 - 12k - 45 = 35 - 9k$ $-12k - 38 = 35 - 9k$ $-3k = 73$ $k = -\frac{73}{3} = -24\frac{1}{3}$