1. 1,5x³ - 2.4y = 0.3(5x³ - 8y)
При x = -1, y = 2, то 0.3(5x³ - 8y) = 0.3(5*(-1)³ - 8*2) = 0.3(-5 - 16) = 0.3 * (-21) = -6.3
Или не преобразовывая: 1,5x³ - 2.4y = 1.5*(-1)³ - 2.4*2 = -1.5 - 4.8 = -6.3
2. -4x³ (x² - 3x +2) = -4x⁵ + 12x⁴ - 8x³
3. (1 - x)(2y - x) = 2y - 2xy - x + x²
4. (5c - 4)² = 25c² - 40c + 16
5. 3a(a-b) + b(2a-b) = 3a³ - 3ab + 2ab - b² = 3a³ - ab - b²