Question

初中数学！求过程！求解答！

1. 如将(x-y)看成一个因式,则合并(x-y)²-3(x-y)-4(x-y)²+5(x-y)的结果是
2. x³-x+4-2x³-2+3x²+2x
3. (-8x²+6x)-(5x²-4x+1)
4. (3a²+2a-1)-(2a²-3a-5)
5. 把（x-y）,(a+b)作为一个因式，合并同类项：
3(x-y)²-9(x-y)²+6(x-y)-1 2(a+b)-5/8(a+b)²-2/3（a+b）+3(a+b)²+2

Answer 1

解：
1、原式=-3（x-y）²2(x-y)
2、原式=-x立方+3x²+x+2=-（x立方-3x²+3x-1）+4x+1=-（x-1）立方+4x+1
3、原式=-8x²+6x-5x²+4x-1=-13x²+10x-1
4、原式=3a²+2a-1-2a²+3a+5=a²+5a+4=（a+4）（a+1）
5、（1）、原式=-6（x-y）²+6（x-y）-1
（2）、原式=19/8（a+b）²+4/3（a+b）+2

Answer 2

1. 如将(x-y)看成一个因式,则合并(x-y)²-3(x-y)-4(x-y)²+5(x-y)的结果是
(x-y)²-3(x-y)-4(x-y)²+5(x-y)=-3(x-y)²+2(x-y)
2. x³-x+4-2x³-2+3x²+2x=-x³+3x²+x+2
3. (-8x²+6x)-(5x²-4x+1)=-3x²+10x-1
4. (3a²+2a-1)-(2a²-3a-5)=a²+5a+4
5. 把（x-y）,(a+b)作为一个因式，合并同类项：
3(x-y)²-9(x-y)²+6(x-y)-1=-6(x-y)²+6(x-y)-1
2(a+b)-5/8(a+b)²-2/3（a+b）+3(a+b)²+2=19/8(a+b)²+4/3（a+b）+2

Answer 3

将x-y 记为 t
1. 则 t²-3t-4t+5t²=6t²-7t 即6（x-y）²-7（x-y）
2.x³-x+4-2x³-2+3x²+2x=-x³+3x²+x+2
3.-3x²-2x-1
4.a²+5a+4
5. -6(x-y)²+6(x-y)-1 19／8(a+b)²+4／3(a+b)+2

Answer 4

(x-y)²-3(x-y)-4(x-y)²+5(x-y)
=-3(x-y)²+2(x-y)

2. x³-x+4-2x³-2+3x²+2x
=x³+3x²+x+2

3. (-8x²+6x)-(5x²-4x+1)
=-8x²+6x-5x²+4x-1
=-13x²+10x-1

4. (3a²+2a-1)-(2a²-3a-5)
=3a²+2a-1-2a²+3a+5
=a²+5a+4

3(x-y)²-9(x-y)²+6(x-y)-1
=-6(x-y)²+6(x-y)-1

2(a+b)-5/8(a+b)²-2/3（a+b）+3(a+b)²+2
=19/8(a+b)²+4/3(a+b)+2