VD1:
\(a,=\dfrac{\left(1-x\right)\left(1+x\right)}{x\left(x-2\right)}\cdot\dfrac{x}{x+1}=\dfrac{1-x}{x-2}\\ b,=\dfrac{\left(x-1\right)\left(x^2+x+1\right)}{x+2}\cdot\dfrac{1}{x^2+x+1}=\dfrac{x-1}{x+2}\\ c,=\dfrac{\left(x-1\right)\left(x+1\right)}{\left(x+2\right)\left(x-1\right)}\cdot\dfrac{\left(x+1\right)\left(x+2\right)}{\left(x-1\right)^2}=\dfrac{\left(x+1\right)^2}{\left(x-1\right)^2}\\ d,=\dfrac{x+2y}{x^2+xy+y^2}\cdot\dfrac{\left(x-y\right)\left(x^2+xy+y^2\right)}{\left(x+2y\right)^2}=\dfrac{x-y}{x+2y}\)
VD2:
\(a,A=\dfrac{x^2}{\left(y+1\right)^2}\cdot\dfrac{y+1}{2x}\cdot\dfrac{y+1}{2x}=\dfrac{1}{4}\\ b,B=\dfrac{x^2}{\left(y+1\right)^2}:\left(\dfrac{2y}{y+1}\cdot\dfrac{y+1}{2x}\right)=\dfrac{x^2}{\left(y+1\right)^2}\cdot1=\dfrac{x^2}{\left(y+1\right)^2}\)
VD1:
\(a,\dfrac{6x}{15y^3}\left(-\dfrac{5y^2}{3x^2}\right)=\dfrac{-2}{3xy}\\ b,=\dfrac{x+1}{x-2}\cdot\dfrac{\left(x-2\right)\left(x+2\right)}{\left(x+1\right)^2}=\dfrac{x+2}{x+1}\\ c,=\dfrac{-3\left(x-1\right)}{\left(x-3\right)\left(x+3\right)}\cdot\dfrac{x-3}{x-1}=\dfrac{-3}{x+3}\\ d,=\dfrac{2\left(3x+2\right)}{\left(x-2\right)\left(x+2\right)}\cdot\dfrac{x\left(x-2\right)}{3x+2}=\dfrac{2x}{x+2}\)
