{3(x+Y)³-5(x+y)²-2x-2y}/(x+y)

{3(x+Y)³-5(x+y)²-2x-2y}/(x+y)
{3(x+Y)³-5(x+y)²-2x-2y}/(x+y)

{3(x+Y)³-5(x+y)²-2x-2y}/(x+y)
原式=[3(x+Y)³-5(x+y)²-2（x+y）]/(x+y)
=3(x+y)²-5(x+y)-2
=3(x+y)(x+y-5)-2
=3x²+6xy＋3y²－5x－5y－2
有什么不懂的可以继续追问,

　　{3(x+Y)³-5(x+y)²-2x-2y}/(x+y)
　　={3(x+Y)³-5(x+y)²-2﹙x+y﹚}/(x+y)
　　=3(x+Y)²-5(x+y)-2
　　＝3x²+6xy＋3y²－5x－5y－2

{3(x+Y)³-5(x+y)²-2x-2y}/(x+y)
=(x+y)[3(x+y)²-5(x+y)-2]/(x+y)
=[3(x+y)+1][(x+y)-2]
=(3x+3y+1)(x+y-2)

不明白可追问，满意请采纳

已知x+y=3
5(x+y)的平方-2x-2y+2
=5(x+y)的平方-2(x+y)+2
=5*3^2-2*3+2
=45-6+2
=41