因式分解题,拆添项,换元,第一题：x³-3x+2第二题：x³-48x+7第三题：x³-5x²+5x-4第四题：x(x+1)(x+2)(x+3)+1第五题：(xy-1)²+(xy-2)(x+y-2xy)

1.=（x^2-2x)-(x-2)
=(x-1)(x-2)
2.=(x^3-7x^2)+(7x^2-49x)+(x-7)
=(x-7)(x^2+7x+1)
3.=(x^3-4x^2)-(x^2-4x)+(x-4)
=(x-4)(x^2-x+1)
4.=(x^2+3x)(x^2+3x+2)+1
=(x^2+3x+1)-1)(x^2+3x+1+1)+1
=(x^2+3x+1)^2
5.=(xy-1)²+(xy-1-1)(x+y-2xy)
=(xy-1)²+(xy-1)(x+y-2xy)-(x+y-2xy)
=(xy-1)(x+y-xy-1)-(x+y-2xy)
= -(xy-1)(x-1）（y-1)-x(y-1)-y(x-1)
5不是很有思路

1..（x^2-2x)-(x-2) =(x-1)(x-2)
2.

1.=（x^2-2x)-(x-2)
=(x-1)(x-2)
2.=(x^3-7x^2)+(7x^2-49x)+(x-7)
=(x-7)(x^2+7x+1)
3.=(x^3-4x^2)-(x^2-4x)+(x-4)
=(x-4)(x^2-x+1)
4.=(x^2+3x)(x^2+3x+2)+1
=(x^2+3x+1)-1)(x^2+3x+1+1)+1
=(x^2+3x+1)^2
5.应该是这个，不然不能分解
（xy-1)²+(x+y-2)(x+y-2xy)
（x+y-2xy)(x+y-2)+(xy-1)2
=(y2-2y+1)x2-2(y2-2y+1)x+y2-2y+1
=(y-1)2(x-1)2

（1）x³-3x+2
=x³-1-3x+3
=（x³-1）-3（x-1）
=（x-1)(x²+x+1)-3（x-1）
=（x-1）(x²+x+1-3)
=（x-1）(x²+x-2）
=（x-1）(x-1)(x+2)
=(x-1)²(x-2)
（2）x³-48x+7
临时有事要下了，如果明天问题还在我就继续回答吧
bye

1,x³-3x+2=(x-1)(x²+x-2)2,x³-48x+7=x³-49x+x+7=x(x-7)(x+7)+x+7=(x²-7x+1)(x+7)3,x³-5x²+5x-4=(x³-4x²)-x²+5x-4 =x²(x-4)-(x-4)(x-1) =(x-4)(x²-x+1)...