б) x² - xy - 4x + 4y = x(x - y) - 4(x - y) = (x - y)(x - 4)
При x = 0,5; y = 2,5 (x - y)(x - 4) = (0,5 - 2,5)(0,5 - 4) = -2 * (-3,5) = 7
г) xb - xc + 3c - 3b = x(b - c) - 3(b - c) = (x - 3)(b - c)
При x = 2; b = 12,5; c = 8,3 (x - 3)(b - c) = (2 - 3)(12,5 - 8,3) = -1 * 4,2 = -4,2
е) 3ax - 4by - 4ay + 3bx = 3ax + 3bx - 4by - 4ay = 3x(a + b) - 4y(a + b) = (a + b)(3x - 4y)
При a = 3; b = -13; x = -1, y = -2 (a + b)(3x - 4y) = (3 - 13)(-3 + 8) = -10 * 5 = -50