解答数学题,要过程(初中)

1.原题有误.
2.12x^5y^4÷(-3x^3y^3)=-4x^2y
3.原题=4a^2bc^3-2a+1
4.原题=(9x^5y^2-8x^5y^7)÷9x^4y^2
=x-8/9xy^5
5.原题=(x^2-x^3-x^4)÷(-1/3x^2)-(x^2-4)
=-3+3x-3x^2-x^2+4
=-4x^2+3x+1
6.原题=9x^2+y^2-6xy-4x^2-y^2-4xy-5x^2+5xy
=-5xy

1.计算:X^m+n·(3X^m Y^n)÷(-2X^m·Y^m).
X^m+n·(3X^m Y^n)÷(-2X^m·Y^m)
=X^m+[3n/(-2)](Y^n÷Y^m)
=X^m-3n*Y(n-m)/2

2.一个单项式与-3X^ 3Y^3 的积是12X^5 Y^4,求这个单项式.
12X^5 Y^4 ÷(-3X^ 3Y^3)=-4X^2Y

3.计算:(12a^3 b^2 c^3 -6a^2 b+3ab)÷3ab.
(12a^3 b^2 c^3 -6a^2 b+3ab)÷3ab
=4a^2 b c^2 -2a+1

4.计算:[(-3XY)^2·X^3-2X^2·(2XY^2)^3·1/2Y]÷9X^4 Y^2.
[(-3XY)^2·X^3-2X^2·(2XY^2)^3·1/2Y]÷9X^4 Y^2
=(9X^5 Y^2- 8X^5 Y^7) ÷9X^4 Y^2
=X- (8/9) X Y^5

5.计算:(X^2-X^3+X^4)÷(-1/3X^2)-(X+2)(X-2).
(X^2-X^3+X^4)÷(-1/3X^2)-(X+2)(X-2)
=-3(1-X+X^2)-(X^2-4)
=-4X^2+3X+1
=(4X+1)(1-X)

6.计算：（3X-Y)^2-(2X+Y)^2-5X(X-Y）
=9X^2+Y^2-6XY-