Nhờ m giúp vs ạ . Phải đặt nhân tử chung hoặc dùng hằng đẳng thức

Bài 5. 1) $\frac{3x^2y}{5xy^4} = \frac{3 \cdot x \cdot x \cdot y}{5 \cdot x \cdot y \cdot y \cdot y \cdot y} = \frac{3x}{5y^3}$ 2) $\frac{4x^2-4x}{x-1} = \frac{4x(x-1)}{x-1} = 4x$ 3) $\frac{5x^2+5x}{3x+3} = \frac{5x(x+1)}{3(x+1)} = \frac{5x}{3}$ 4) $\frac{ab^2-a^2b}{2a^2+a} = \frac{ab(b-a)}{a(2a+1)} = \frac{b(b-a)}{2a+1}$ 5) $\frac{12(x^4-1)}{18(x^2-1)} = \frac{12(x^2+1)(x^2-1)}{18(x+1)(x-1)} = \frac{12(x^2+1)(x+1)(x-1)}{18(x+1)(x-1)} = \frac{2(x^2+1)}{3}$ 6) $\frac{12x^2y(x+y)}{18xy(x+y)^3} = \frac{12x \cdot x \cdot y \cdot (x+y)}{18x \cdot y \cdot (x+y) \cdot (x+y) \cdot (x+y)} = \frac{2x}{3(x+y)^2}$ 7) $\frac{x^3-36x}{x^2+6x} = \frac{x(x^2-36)}{x(x+6)} = \frac{x(x+6)(x-6)}{x(x+6)} = x-6$ 8) $\frac{x^2-10x+25}{x^2-5x} = \frac{(x-5)(x-5)}{x(x-5)} = \frac{x-5}{x}$