c) $\frac{4}{15.$x^{3}$.$y^{5}$}$ và $\frac{11}{12.$x^{4}$.$y^{2}$ }$ MTC: 60$x^{4}$ .$x^{5}$
Có: $\frac{4}{15.$x^{3}$.$y^{5}$}$=$\frac{4.4.x}{60$x^{4}$ .$x^{5}$}$=$\frac{16x}{60$x^{4}$ .$x^{5}$}$
$\frac{11}{12.$x^{4}$.$y^{2}$ }$=$\frac{11.5.y³}{60$x^{4}$ .$x^{5}$}$=$\frac{55y³}{60$x^{4}$ .$x^{5}$}$
d) $\frac{2x}{x²-8x+16}$ và $\frac{x}{3x²-12x}$
$\frac{2x}{x²-8x+16}$=$\frac{2x}{(x-4)²}$
$\frac{x}{3x²-12x}$=$\frac{x}{3x.(x-4)}$
⇒ MTC: 3x.(x-4)²
Có: $\frac{2x}{x²-8x+16}$=$\frac{2x}{(x-4)²}$=$\frac{2x.3x}{3x.(x-4)²}$=$\frac{6x²}{3x.(x-4)²}$
$\frac{x}{3x²-12x}$=$\frac{x}{3x.(x-4)}$=$\frac{x.(x-4)}{3x.(x-4)²}$=$\frac{x²-4x}{3x.(x-4)²}$