a)MTC : 12x5y4
$\frac{5}{x^5y^3}$ = $\frac{5.12y}{x^5y^3.12y}$ $\frac{60y}{12x^5y^4}$
$\frac{7}{12x^3y4}$ = $\frac{7.x^2}{12x^3.y^4.x^2}$ = $\frac{7x^2}{12x^5y^4}$
b)MTC : 60x4y5
$\frac{4}{15x^3y^5}$ = $\frac{4.4x}{15x^3y^5.4x}$ = $\frac{16x}{60x^4y^5}$
$\frac{11}{12x^4y^5}$ = $\frac{11.5y^3}{12x^4y^2.5y^3}$ = $\frac{55x}{60x^4y^5}$
chúc bạn học tốt