Lời giải :
`a)x^3+3x=x(x^2+3)`
`b)4x-8y=4(x-2y)`
`c)8(x+3y)-16x(x+3y)=(x+3y)(8-16x)=8(x+3y)(1-2x)`
`d)3(x-y)-5x(y-x)=3(x-y)+5x(x-y)=(3+5x)(x-y)`
`e)9x^2-6x=3x(3x-2)`
`f)x^4y-2x^2y^2+5xy=xy(x^3-2xy+5)`
`g)4x^2(x+1)+2x^2(x+1)=(4x^2+2x^2)(x+1)=6x^2(x+1)`
`h)4/3 x(y-2)-2/5 y(2-y)=4/3x(y-2)+2/5y(y-2)=(4/3x+2/5y)(y-2)`