计算：3x³-3x²-y²+5y+x²-5y+y²

计算：3x³-3x²-y²+5y+x²-5y+y²

3x³-3x²-y²+5y+x²-5y+y²
=3x³-(3-1)x²+(1-1)y²+(5-5)y
=3x³-2x²

3x³-3x²-y²+5y+x²-5y+y²
=3x³+(x²-3x²)+(y²-y²)+(5y-5y)
=3x³-2x²

合并同类项！把字母相同且指数相同的归一类，对应的系数提出来相加减
3x³-3x²-y²+5y+x²-5y+y²=3x³-(3-1)x²+(1-1)y²+(5-5)y=3x³-2x²