a) Ta có: \(\dfrac{2^3-x^3}{x\left(x^2+2x+4\right)}\)
\(=\dfrac{\left(2-x\right)\left(4+2x+x^2\right)}{x\left(x^2+2x+4\right)}\)
\(=\dfrac{2-x}{x}=\dfrac{x-2}{-x}\)(đpcm)
b) Ta có: \(\dfrac{-3x\left(x-y\right)}{y^2-x^2}\)
\(=\dfrac{3x\left(x-y\right)}{\left(x-y\right)\left(x+y\right)}\)
\(=\dfrac{3x}{x+y}\)(đpcm)
c) Ta có: \(\dfrac{3a\left(x+y\right)^2}{9a^2\left(x+y\right)}\)
\(=\dfrac{3a\left(x+y\right)^2}{3a\cdot3a\left(x+y\right)}\)
\(=\dfrac{x+y}{3a}\)(đpcm)
a) Ta có: =(2−x)(4+2x+x2)x(x2+2x+4)=(2−x)(4+2x+x2)x(x2+2x+4)
−3x(x−y)y2−x2−3x(x−y)y2−x2
=3xx+y=3xx+y(đpcm)
c) Ta có: =3a(x+y)23a⋅3a(x+y)=3a(x+y)23a⋅3a(x+y)
