1.已知a+b=2,a•b=-8,求a^2(a+b)-ab(a+b)+b^2(a+b)2.因式分解(xy+1)(x+1)(y+1)+xy咋做?

1.已知a+b=2,a•b=-8,求a^2(a+b)-ab(a+b)+b^2(a+b)2.因式分解(xy+1)(x+1)(y+1)+xy咋做?

a^2(a+b)-ab(a+b)+b^2(a+b)
=2(a²-ab+b²)
=2(a²+2ab+b²-3ab)
=2[(a+b)²-3ab]
=2[4+24]
=56
(xy+1)(x+1)(y+1)+xy
=(xy+1)(xy+1+x+y)+xy
=(xy+1)(xy+1+x)+y(xy+1)+xy
=(xy+1)(xy+1+x)+y(xy+1+x)
=(xy+1+x)(xy+y+1) .