-(3x平方y+10x立方)+3x立方+6x立方y+3x平方y-(6x立方y-7x立方)
=-3x²y-10x³+3x³+6x³y+3x²y-6x³y+7x³
=(-3x²y+3x²y)+(6x³y-6x³y)+(3x³+7x³-10x³)
=0+0+0
=0
-(3x平方y+10x立方)+3x立方+6x立方y+3x平方y-(6x立方y-7x立方)
=-3x²y-10x³+3x³+6x³y+3x²y-6x³y+7x³
=(-3x²y+3x²y)+(6x³y-6x³y)+(3x³+7x³-10x³)
=0+0+0
=0