2x²y+4x²y-3xy²-5xy²,其中x=1,y=-1

2x²y+4x²y-3xy²-5xy²,其中x=1,y=-1
2x²y+4x²y-3xy²-5xy²,其中x=1,y=-1

2x²y+4x²y-3xy²-5xy²,其中x=1,y=-1
2x²y+4x²y-3xy²-5xy²
=6x²y-8xy²
=6×1²×(-1)-8×1×(-1)²
=6×1×(-1)-8×1×1
=-6-8
=-14

负14
负2+负4-3-5=负14
望采纳，谢谢