1.
a). 2c² + 7c = c(2c + 7)
b). 4y² - 28y = 4y(y - 7)
c). 24x²y² - 6y² = 6y²(4x² - 1) = 6y²(2x - 1)(2x + 1)
d). 3x⁴ + 15x² + 9x = 3x(x³ + 5x + 3)
2.
a). x(b - c) + 7b - 7c = x(b - c) + 7(b - c) = (x + 7)(b - c)
b). 3x - 3y + ax - ay = 3(x - y) + a(x - y) = (3 + a)(x - y)
c). xy + 5x - by - 5b = x(y + 5) - b(y + 5) = (x - b)(y + 5)
d). x⁴ - 3x³ + 5x - 15 = x³(x - 3) + 5(x - 3) = (x³ + 5)(x - 3)
3. am² - 2m² - ba + 2b + 2a - a² = m²(a - 2) - b(a - 2) - a(a - 2) =
= (m² - b - a)(a - 2)