已知A=x³-2y³+3x²y+xy²-3xy+4,B=y³-x³-4x²y-3xy-3xy²+3.C=y³+x²y+2xy²+6xy-6,试说明对于xyz的任何值A+B+C是常数.

已知A=x³-2y³+3x²y+xy²-3xy+4,B=y³-x³-4x²y-3xy-3xy²+3.C=y³+x²y+2xy²+6xy-6,试说明对于xyz的任何值A+B+C是常数.
已知A=x³-2y³+3x²y+xy²-3xy+4,B=y³-x³-4x²y-3xy-3xy²+3.
C=y³+x²y+2xy²+6xy-6,试说明对于xyz的任何值A+B+C是常数.

已知A=x³-2y³+3x²y+xy²-3xy+4,B=y³-x³-4x²y-3xy-3xy²+3.C=y³+x²y+2xy²+6xy-6,试说明对于xyz的任何值A+B+C是常数.
已知A=x³-2y³+3x²y+xy²-3xy+4,B=y³-x³-4x²y-3xy-3xy²+3.C=y³+x²y+2xy²+6xy-6,
试说明对于xyz的任何值A+B+C是常数.
A+B+C
= ( x³-2y³+3x²y+xy²-3xy+4) + (y³-x³-4x²y-3xy-3xy²+3) +( y³+x²y+2xy²+6xy-6)
= x³-2y³+3x²y+xy²-3xy+4 +y³-x³-4x²y-3xy-3xy²+3 + y³+x²y+2xy²+6xy-6
= 4 +3 -6
= 1