2. a) 1 - 2y^2 + 4y - 3y - 6
-2y^2 + y + 7
б) (0,8a^3 + 1,2a)(5-3a^2)
4a^3 - 2,4^5 + 6a - 3,6a^3
0,4a^3 - 2,4a^5 + 6a
3. 1 способ: (- 22/3 * 11/3) - (5/3 * 2/3)
-242/9 - 10/9 = -252/9 = -28
2 способ: b^2 + 4b - 7b - 28 - (b^2 + 3b + 2)
b^2 + 4b - 7b - 38 - b^2 - 3b - 2
-6b - 30
-6 * (-1/3) - 30 = - 28
5. a) 5x^2 + x = 0
x(5x + 1) = 0
x1= 0; x2 = -1/5
б) 12x^2 - (12x^2 + 4x - 9x - 3) = 0
12x^2 - 12x^2 + 5x + 3 = 0
5x = -3
x = -3/5