5) 5a - 5b + ay - by = 5(a - b) + y(a - b) = (a - b)(5 + y)
6) 27x³y² - 36x⁴y³ + 18x⁵y = 9x³y(3y - 4xy² + 2x²) = 9x³y(2x(x - 2y²) + 3y)
7) c(b - 5) - a³(5 - b) = c(b - 5) + a³(b - 5) = (b - 5)(c + a³)
8) 2cx - cy - 6x + 3y = 2x(c - 3) - y(c - 3) = (2x - y)(c - 3)
9) cd² - xd² - bc + bx + d² - b = d²(c - x + 1) - b(c - x + 1) = (d² - b)(c - x + 1)