a)MTC:\(12x^5y^4\)

\(\dfrac{5}{x^5y^3}=\dfrac{5\cdot12y}{x^5y^3\cdot12y}=\dfrac{60y}{12x^5y^4}\)

\(\dfrac{7}{12x^3y^4}=\dfrac{7\cdot x^2}{12x^3y^4\cdot x^2}=\dfrac{7x^2}{12x^5y^4}\)

b)MTC:\(60x^4y^5\)

\(\dfrac{4}{15x^3y^5}=\dfrac{4\cdot4x}{15x^3y^5\cdot4x}=\dfrac{16x}{60x^4y^5}\)

\(\dfrac{11}{12x^4y^2}=\dfrac{11\cdot5y^3}{12x^4y^2\cdot5y^3}=\dfrac{55y^3}{60x^4y^5}\)

\(\dfrac{5}{x^5y^3};\dfrac{7}{12x^3y^4}\)

\(MTC=12x^5y^4\)

Ta có:

\(\dfrac{5}{x^5y^3}=\dfrac{60y}{12x^5y^4}\)

\(\dfrac{7}{12x^3y^4}=\dfrac{7x^2}{12x^5y^4}\)

ngu

a) MTC: 2xy

Quy đồng: \(\frac{2x-3y}{2xy}\) giữ nguyên

               \(\frac{x+2y}{x}=\frac{2y\left(x+2y\right)}{2xy}=\frac{2xy+y^2}{2xy}\)

b) \(\frac{2}{x^2-4x}=\frac{2}{x\left(x-4\right)};\frac{x}{x^2-16}=\frac{x}{\left(x-4\right)\left(x+4\right)}\)

MTC: x (x-4)(x+4)

Quy đồng : \(\frac{2}{x\left(x-4\right)}=\frac{2\left(x+4\right)}{x\left(x-4\right)\left(x+4\right)}=\frac{2x+8}{x\left(x-4\right)\left(x+4\right)}\)

               \(\frac{x}{\left(x+4\right)\left(x-4\right)}=\frac{x^2}{x\left(x-4\right)\left(x+4\right)}\)

Học tốt nhé ^3^

Bài 2:

a: \(\dfrac{1}{2x^3y}=\dfrac{6yz^3}{12x^3y^2z^3}\)

\(\dfrac{2}{3xy^2z^3}=\dfrac{2\cdot4x^2}{12x^3y^2z^3}=\dfrac{8x^2}{12x^3y^2z^3}\)

\(\dfrac{x^2-4}{x^2+2x}=\dfrac{\left(x-2\right)\left(x+2\right)}{x\left(x+2\right)}=\dfrac{x-2}{x}=\dfrac{\left(x-2\right)^2}{x\left(x-2\right)}\)

\(\dfrac{x}{x-2}=\dfrac{x^2}{x\left(x-2\right)}\)

Để x;y;z ra ngoài làm thừa số chung rồi quất hết phần còn lại vào ngoặc thì thành 2 nhân tử thôi bạn, kiểu như phân phối ý.