Question

x+y=1,xy=-1/2,求x(x+y)(x-y)-x(x+y)2

Answer 1

解:原式=x(x+y)(x-y-x-y)
=-2xy(x+y)
=-1

追问

7(x-1)3-14(x-1)2+7(x-1)

追答

你没写错吧。数字怎么在括号后面？而且和括号之间什么都没。。

Answer 2

原式=x(x+y)(x-y-2)
=x(x+y)(x-y-x-y)
=-2yx(x+y)
=-2×（-1/2）×1
=1

Answer 3

x(x+y)(x-y)-x(x+y)2 =x(x+y)[(x-y）－（x+y）]
=x（x＋y）（－2y）=－2xy（x＋y）
=－2×（－1/2）×1
=1

追问

18p3q3-2pq

追答

7(x-1)3-14(x-1)2+7(x-1)=7（x-1)[﹙x－1﹚²－2﹙x-1﹚＋1]=7﹙x－1﹚[﹙x－1﹚－1]²
=7﹙x－1﹚﹙x－2﹚²

Answer 4

x(x+y)(x-y)-x(x+y)²
=x(x+y)(x-y-x-y)
=-2yx(x+y)
=-2×（-1/2）×1
=1

追问

a+b=2,ab=2求1/2a3b+a2b2+1/2ab3

追答

1/2a³b+a²b²+1/2ab³
=1/2*ab(a²+2ab+b²)
=1/2*ab(a+b)²
=1/2*2*2²
=4
18p3q3-2pq
=2pq(9p²q²-1)
=2pq(3pq+1)(3pq-1)
7(x-1)3-14(x-1)2+7(x-1)
=7(x-1)[(x-1)²-2(x-1)+1]
=7(x-1)(x-1-1)²
=7(x-1)(x-2)²