计算:(1)-3(x2-xy)-x(-2y+2x)(2)(-x5)?x3n-1+x3n?(-x)4(3)(x+2)(y+3)-(x+1)(y-2)

计算:(1)-3(x2-xy)-x(-2y+2x)(2)(-x5)?x3n-1+x3n?(-x)4(3)(x+2)(y+3)-(x+1)(y-2)(4)(-2m2n)3?mn+(-7m7n12)0-2(mn)-4?m11?n8(5)(5x2y3-4x3y2+6x)÷6x,其中x=-2,y=2(6)(3mn+1)(3mn-1)-(3mn-2)2(7)(3a2b)3?(-2ab4)2÷(6a5b3)

(1)原式=-3x2+3xy+2xy+2x2
=5xy-x2
(2)原式=-x5+3n-1+x3n+4
=-x3n+4+x3n+4
=0;
(3)原式=xy+3x+2y-6-xy+2x-y+2
=5x+y-4;
(4)原式=-8m6n3?mn+1-2m-4n-4?m11?n8
=-8m7n4-2m7n4+1
=-10m7n4+1;
(5)原式=5x2y3÷6x-4x3y2÷6x+6x÷6x,
=
5
6
xy3-
2
3
x2y2+1;
∵x=-2,y=2
∴原式=
5
6
×2×8-
2
3
×4×4+1;
=
40
3
-
32
3
+1
=
11
3

(6)原式=(3mn)2-1-(3mn-2)2
=(3nm+3mn-2)(3mn-3mn+2)-1
=2(6mn-2)-1
=12mn-5;
(7)原式=27a6b3?4a2b8÷6a5b3
=
27×4
6
a8-5b3+8-3
=18a3b8
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