\(a,\dfrac{2x^2y^5}{3x^4y^2}=\dfrac{2x^2y^2.y^3}{3x^2y^2.x^2}=\dfrac{2y^3}{3x^2}\\ b,\dfrac{3x\left(x-y\right)^3}{2x^2\left(x-y\right)^2}=\dfrac{3x\left(x-y\right)^2.\left(x-y\right)}{2x.x\left(x-y\right)^2}=\dfrac{3\left(x-y\right)}{2x}\left(Với:x\ne y\right)\\ c,\dfrac{3x^2y+4xy^2}{6x+8y}=\dfrac{xy\left(3x+4y\right)}{2\left(3x+4y\right)}=\dfrac{xy}{2}\)
\(d,\dfrac{-3x^2-6x}{4-x^2}=\dfrac{-3x\left(x+2\right)}{\left(2-x\right)\left(2+x\right)}=\dfrac{-3x}{2-x}\\ e,\dfrac{x^2+3x-4}{x-1}=\dfrac{x^2+4x-x-4}{x-1}\\ =\dfrac{x\left(x+4\right)-\left(x+4\right)}{x-1}=\dfrac{\left(x-1\right)\left(x+4\right)}{x-1}=x+4\)
