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)