Итоговая контрольная по алгебре.

Хвалю за честность.
1) (-3/4) * x^2 * (x + 3) = (-3/4) * 16 * (-1) = 12
2)3x - 2(5x - 4) = 6(2 - 3x) + 7
3x - 10x + 8 = 12 - 18x + 7
-7x + 8 = 19 - 18x
11x = 11
x = 1
3)(2 + c)(2 - c) + (c -3)^2 - 3(4 - 2c) = 4 - c^2 + c^2 - 6c + 9 - 12 + 6c = 1
4) a) 18a^2 - 2b^2 = 2(9a^2 - b^2) = 2(3a - b)(3a + b)
b) 6c^4 - 48a^3c = 6c(c^3 - 8a^3) = 6c(c - 2a)(c^2 + 2ac + 4a^2)
5) 3x - 4y = 24 -> x = (24 + 4y)/3
5x + 7y = -1
5*(24 + 4y)/3 + 7y = -1
40 + (20y + 21y)/3 = -1
41y = -41*3 = -123
y = -123/41 = -3
x = (24 + 4y)/3 = (24 - 12)/3 = 4
6) x1 + x2 = 10 -> x1 = 10 - x2
x1 - x2 = 26
10 - x2 - x2 = 26
-2 * x2 = 16
x2 = -8
x1 = 10 - x2 = 18
7) x1 + x2 = 110 -> x2 = 110 - x1
x1 + x2/2 = 4 * x2/2
x1 = 1.5 * x2
x1 = 1.5(110 - x1) = 165 - 1.5*x1
x1 = 165/2.5 = 66
x2 = 110 - 66 = 44
8) Графики постройте сами. Тем паче, что для первый - прямая, достаточно двух точек.