1)15x + 18y = 3(5x + 6y); 2) 3xy - 5y = y(3x - 5); 3) a⁴ + a³ = a³(a + 1); 4) 2y⁵ - 4y³ = 2y³(y² - 2) = 2y³(y - √2)(y + √2); 5) 5ab + 10a² = 5a(b + 2a); 6) ax² + 3ax = ax(x + 3); 7) xy³ + 5x²y² - 3x²y = xy(y² + 5xy - 3x); 8) 5(2 - a) + 3a(2 - a) =
(2 - a)(5 + 3a); 9) x(x - y) -3(y - x) =x(x - y) +3(x - y) = (x - y)(x + 3); 10) 10m⁵n² + 15nm⁷ = 5m⁵n(2n + 3m²); 11) 8x⁶y² + 24y²x³ - 16x⁵y⁵ = 8x³y²(x³ + 3 - 2x²y³);
12) (x - 3)(3x + 1) + (3 - x)(3 + x) = (x - 3)(3x + 1) - (x - 3)(3 + x) = (x - 3)(3x + 1 - 3 - x) = (x - 3)(2x - 2) = 2(x - 3)(x - 1); 13) a³(a + 6)² - 3a⁴(6 + a) =
a³(a + 6)(a + 6 - 3a) = a³(a + 6)(6 - 2a) = 2a³(a + 6)(3 - a)